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Hiroshige T, Uemura KI, Nakamura KI, Igawa T. Insights on Platelet-Derived Growth Factor Receptor α-Positive Interstitial Cells in the Male Reproductive Tract. Int J Mol Sci 2024; 25:4128. [PMID: 38612936 PMCID: PMC11012365 DOI: 10.3390/ijms25074128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 03/31/2024] [Accepted: 04/04/2024] [Indexed: 04/14/2024] Open
Abstract
Male infertility is a significant factor in approximately half of all infertility cases and is marked by a decreased sperm count and motility. A decreased sperm count is caused by not only a decreased production of sperm but also decreased numbers successfully passing through the male reproductive tract. Smooth muscle movement may play an important role in sperm transport in the male reproductive tract; thus, understanding the mechanism of this movement is necessary to elucidate the cause of sperm transport disorder. Recent studies have highlighted the presence of platelet-derived growth factor receptor α (PDGFRα)-positive interstitial cells (PICs) in various smooth muscle organs. Although research is ongoing, PICs in the male reproductive tract may be involved in the regulation of smooth muscle movement, as they are in other smooth muscle organs. This review summarizes the findings to date on PICs in male reproductive organs. Further exploration of the structural, functional, and molecular characteristics of PICs could provide valuable insights into the pathogenesis of male infertility and potentially lead to new therapeutic approaches.
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Affiliation(s)
- Tasuku Hiroshige
- Department of Urology, Kurume University School of Medicine, Kurume 830-0011, Japan
| | - Kei-Ichiro Uemura
- Department of Urology, Kurume University School of Medicine, Kurume 830-0011, Japan
| | - Kei-Ichiro Nakamura
- Cognitive and Molecular Research Institute of Brain Diseases, Kurume University School of Medicine, Kurume 830-0011, Japan
| | - Tsukasa Igawa
- Department of Urology, Kurume University School of Medicine, Kurume 830-0011, Japan
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Amberg GC, Lee JY, Koh SD, Sanders KM. Characterization of the A-type potassium current in murine gastric fundus smooth muscles. Am J Physiol Cell Physiol 2021; 321:C684-C693. [PMID: 34432539 PMCID: PMC8560387 DOI: 10.1152/ajpcell.00247.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 11/22/2022]
Abstract
Transient outward, or "A-type," currents are rapidly inactivating voltage-gated potassium currents that operate at negative membrane potentials. A-type currents have not been reported in the gastric fundus, a tonic smooth muscle. We used whole cell voltage clamp to identify and characterize A-type currents in smooth muscle cells (SMCs) isolated from murine fundus. A-type currents were robust in these cells with peak amplitudes averaging 1.5 nA at 0 mV. Inactivation was rapid with a time constant of 71 ms at 0 mV; recovery from inactivation at -80 mV was similarly rapid with a time constant of 75 ms. A-type currents in fundus were blocked by 4-aminopyridine (4-AP), flecainide, and phrixotoxin-1 (PaTX1). Remaining currents after 4-AP and PaTX1 displayed half-activation potentials that were shifted to more positive potentials and showed incomplete inactivation. Currents after tetraethylammonium (TEA) displayed half inactivation at -48.1 ± 1.0 mV. Conventional microelectrode and contractile experiments on intact fundus muscles showed that 4-AP depolarized membrane potential and increased tone under conditions in which enteric neurotransmission was blocked. These data suggest that A-type K+ channels in fundus SMCs are likely active at physiological membrane potentials, and sustained activation of A-type channels contributes to the negative membrane potentials of this tonic smooth muscle. Quantitative analysis of Kv4 expression showed that Kcnd3 was dominantly expressed in fundus SMCs. These data were confirmed by immunohistochemistry, which revealed Kv4.3-like immunoreactivity within the tunica muscularis. These observations indicate that Kv4 channels likely form the A-type current in murine fundus SMCs.
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Affiliation(s)
- Gregory C Amberg
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Ji Yeon Lee
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
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Parsons SP, Huizinga JD. Nitric Oxide Is Essential for Generating the Minute Rhythm Contraction Pattern in the Small Intestine, Likely via ICC-DMP. Front Neurosci 2021; 14:592664. [PMID: 33488345 PMCID: PMC7817771 DOI: 10.3389/fnins.2020.592664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/25/2020] [Indexed: 12/16/2022] Open
Abstract
Nitrergic nerves have been proposed to play a critical role in the orchestration of peristaltic activities throughout the gastrointestinal tract. In the present study, we investigated the role of nitric oxide, using spatiotemporal mapping, in peristaltic activity of the whole ex vivo mouse intestine. We identified a propulsive motor pattern in the form of propagating myogenic contractions, that are clustered by the enteric nervous system into a minute rhythm that is dependent on nitric oxide. The cluster formation was abolished by TTX, lidocaine and nitric oxide synthesis inhibition, whereas the myogenic contractions, occurring at the ICC-MP initiated slow wave frequency, remained undisturbed. Cluster formation, inhibited by block of nitric oxide synthesis, was fully restored in a highly regular rhythmic fashion by a constant level of nitric oxide generated by sodium nitroprusside; but the action of sodium nitroprusside was inhibited by lidocaine indicating that it was relying on neural activity, but not rhythmic nitrergic nerve activity. Hence, distention-induced activity of cholinergic nerves and/or a co-factor within nitrergic nerves such as ATP is also a requirement for the minute rhythm. Cluster formation was dependent on distention but was not evoked by a distention reflex. Block of gap junction conductance by carbenoxolone, dose dependently inhibited, and eventually abolished clusters and contraction waves, likely associated, not with inhibition of nitrergic innervation, but by abolishing ICC network synchronization. An intriguing feature of the clusters was the presence of bands of rhythmic inhibitions at 4-8 cycles/min; these inhibitory patches occurred in the presence of tetrodotoxin or lidocaine and hence were not dependent on nitrergic nerves. We propose that the minute rhythm is generated by nitric oxide-induced rhythmic depolarization of the musculature via ICC-DMP.
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Affiliation(s)
- Sean P. Parsons
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Jan D. Huizinga
- Department of Medicine and School of Biomedical Engineering, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
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Lee JH, Wu WH, Huang XY, Jun JY, Choi S. Transient Receptor Potential Canonical 4 and 5 Channel Antagonist ML204 Depolarized Pacemaker Potentials of Interstitial Cells of Cajal. J Neurogastroenterol Motil 2020; 26:521-528. [PMID: 32321198 PMCID: PMC7547197 DOI: 10.5056/jnm20064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/17/2020] [Accepted: 04/21/2020] [Indexed: 01/04/2023] Open
Abstract
Background/Aims To investigate an effect of ML204 (an inhibitor of transient receptor potential canonical 4 and 5 [TRPC4/5] channels) on interstitial cells of Cajal (ICCs) and therefore determine whether TRPC4/5 channels act on ICC-generated pacemaker activity. Methods We enforced whole cell patch clamp analysis, measurements of the intracellular Ca2+ concentration, and reverse transcription polymerase chain reaction to determine the effect of ML204 (10 μM) or englerin A (a selective activator of TRPC4/5 channeles, 10 μM) and the existence of TRPC4/5 in mouse small intestinal ICC. Results Treatment of ICCs with ML204 or englerin A caused the membrane potentials to depolarize. This depolarization effect of membrane potentials by ML204 in ICCs was observed to be concentration-dependent. After treating Ca2+- and Na+-free solutions or flufenamic acid (a non-selective cation channel blocker), the pacemaker potentials in the ICCs were abolished. A specific anoctamin 1 channel blocker did not have any effect on the pacemaker activity in ML204-untreated control cells; however, they blocked ML204-induced pacemaker activity in ICCs. Specific primers designed against TRPC4 and TRPC5 detected the presence of TRPC4/5 in small intestinal ICCs, and the application of ML204 increased raise the frequency of Ca2+ oscillations in ICCs, as assessed using Fluo-4 AM. Conclusion The results implied that ML204 could not inhibit the pacemaker activity but depolarized the membrane potential of ICCs by regulating intracellular Ca2+ oscillations and anoctamin 1 channels.
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Affiliation(s)
- Jun Hyung Lee
- Department of Internal Medicine, College of Medicine, Chosun University, Gwangju, Korea
| | - Wen-Hao Wu
- Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea
| | - Xing-You Huang
- Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea
| | - Jae Yeoul Jun
- Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea
| | - Seok Choi
- Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea
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Fleming MA, Ehsan L, Moore SR, Levin DE. The Enteric Nervous System and Its Emerging Role as a Therapeutic Target. Gastroenterol Res Pract 2020; 2020:8024171. [PMID: 32963521 PMCID: PMC7495222 DOI: 10.1155/2020/8024171] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/03/2020] [Accepted: 08/24/2020] [Indexed: 02/08/2023] Open
Abstract
The gastrointestinal (GI) tract is innervated by the enteric nervous system (ENS), an extensive neuronal network that traverses along its walls. Due to local reflex circuits, the ENS is capable of functioning with and without input from the central nervous system. The functions of the ENS range from the propulsion of food to nutrient handling, blood flow regulation, and immunological defense. Records of it first being studied emerged in the early 19th century when the submucosal and myenteric plexuses were discovered. This was followed by extensive research and further delineation of its development, anatomy, and function during the next two centuries. The morbidity and mortality associated with the underdevelopment, infection, or inflammation of the ENS highlight its importance and the need for us to completely understand its normal function. This review will provide a general overview of the ENS to date and connect specific GI diseases including short bowel syndrome with neuronal pathophysiology and current therapies. Exciting opportunities in which the ENS could be used as a therapeutic target for common GI diseases will also be highlighted, as the further unlocking of such mechanisms could open the door to more therapy-related advances and ultimately change our treatment approach.
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Affiliation(s)
- Mark A. Fleming
- Department of Surgery, Division of Pediatric Surgery, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Lubaina Ehsan
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology, and Nutrition, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Sean R. Moore
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology, and Nutrition, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Daniel E. Levin
- Department of Surgery, Division of Pediatric Surgery, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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7
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Kostin S. Cardiac telocytes in normal and diseased hearts. Semin Cell Dev Biol 2016; 55:22-30. [DOI: 10.1016/j.semcdb.2016.02.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/16/2016] [Indexed: 12/28/2022]
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8
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Balemba OB, Stark TD, Lösch S, Patterson S, McMillan JS, Mawe GM, Hofmann T. (2R,3S,2'' R,3''R)-manniflavanone, a new gastrointestinal smooth muscle L-type calcium channel inhibitor, which underlies the spasmolytic properties of Garcinia buchananii stem bark extract. J Smooth Muscle Res 2016; 50:48-65. [PMID: 26081368 PMCID: PMC4826780 DOI: 10.1540/jsmr.50.48] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Garcinia buchananii Baker stem bark extract (GBB) is a traditional
medication of diarrhea and dysentery in sub-Saharan Africa. It is believed that GBB causes
gastrointestinal smooth muscle relaxation. The aim of this study was to determine whether
GBB has spasmolytic actions and identify compounds underlying these actions. Calcium
(Ca2+) imaging was used to analyze the effect of GBB on Ca2+
flashes and Ca2+ waves in guinea pig gallbladder and distal colon smooth
muscle. Intracellular microelectrode recording was used to determine the effect of GBB,
six fractions of GBB, M1–5 and M7, and
(2R,3S,2”R,3”R)-manniflavanone,
a compound isolated from M3 on action potentials in gallbladder smooth muscle. The
technique was also used to analyze the effect of GBB, M3, and
(2R,3S,2”R,3”R)-manniflavanone
on action potentials in the circular muscle of mouse and guinea pig distal colons, and the
effect of GBB and
(2R,3S,2”R,3”R)-manniflavanone
on slow waves in porcine ileum. GBB inhibited Ca2+ flashes and Ca2+
waves. GBB, M3 and
(2R,3S,2”R,3”R)-manniflavanone
inhibited action potentials. L-type Ca2+ channel activator Bay K 8644 increased
the discharge of action potentials in mouse colon but did not trigger or increase action
potentials in the presence of GBB and
(2R,3S,2”R,3”R)-manniflavanone.
GBB and
(2R,3S,2”R,3”R)-manniflavanone
inhibited action potentials in the presence of Bay K 8644. GBB and
(2R,3S,2”R,3”R)-manniflavanone
reduced the amplitude but did not alter the frequency of slow waves in the porcine ileum.
In conclusion, GBB and
(2R,3S,2”R,3”R)-manniflavanone
relax smooth muscle by inhibiting L-type Ca2+ channels, thus have potential for
use as therapies of gastrointestinal smooth muscle spasms, and arrhythmias.
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Affiliation(s)
- Onesmo B Balemba
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States
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Tanahashi Y, Wang B, Murakami Y, Unno T, Matsuyama H, Nagano H, Komori S. Inhibitory effects of SKF96365 on the activities of K(+) channels in mouse small intestinal smooth muscle cells. J Vet Med Sci 2015; 78:203-11. [PMID: 26498720 PMCID: PMC4785108 DOI: 10.1292/jvms.15-0346] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In order to investigate the effects of SKF96365 (SKF), which is a non-selective cationic channel blocker, on
K+ channel currents, we recorded currents through ATP sensitive K+ (IKATP),
voltage-gated K+ (IKv) and Ca2+ activated K+ channels
(IBK) in the absence and presence of SKF in single small intestinal myocytes of mice with
patch-clamp techniques. SKF (10 µM) reversibly abolished IKATP that was induced by
cromakalim (10 µM), which is a selective ATP sensitive K+ channel opener. These
inhibitory effects were induced in a concentration-dependent and voltage-independent manner. The 50%
inhibitory concentration (IC50) was 0.85 µM, which was obviously lower than that
reported for the muscarinic cationic current. In addition, SKF (1 µM ≈ the IC50
value in IKATP suppression) reversibly inhibited the IKv that was induced by repetitive
depolarizing pulses from −80 to 20 mV. However, the extent of the inhibitory effects was only ~30%. In
contrast, SKF (1 µM) had no significant effects on spontaneous transient IBK and
caffeine-induced IBK. These results indicated that SKF inhibited ATP sensitive K+
channels and voltage-gated K+ channels, with the ATP sensitive K+ channels being more
sensitive than the voltage-gated K+ channels. These inhibitory effects on K+ channels
should be considered when SKF is used as a cationic channel blocker.
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Affiliation(s)
- Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555, Japan
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10
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Fintl C, Hudson NPH, Handel I, Pearson GT. The effect of temperature changes onin vitroslow wave activity in the equine ileum. Equine Vet J 2015; 48:218-23. [DOI: 10.1111/evj.12401] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 12/17/2014] [Indexed: 12/19/2022]
Affiliation(s)
- C. Fintl
- Norwegian University of Life Sciences; Faculty of Veterinary Medicine and Biosciences; Oslo Norway
| | - N. P. H. Hudson
- Royal (Dick) School of Veterinary Studies and Roslin Institute; University of Edinburgh; Roslin Midlothian UK
| | - I. Handel
- Royal (Dick) School of Veterinary Studies and Roslin Institute; University of Edinburgh; Roslin Midlothian UK
| | - G. T. Pearson
- Royal (Dick) School of Veterinary Studies and Roslin Institute; University of Edinburgh; Roslin Midlothian UK
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Mazet B. Gastrointestinal motility and its enteric actors in mechanosensitivity: past and present. Pflugers Arch 2014; 467:191-200. [PMID: 25366494 DOI: 10.1007/s00424-014-1635-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 10/14/2014] [Accepted: 10/19/2014] [Indexed: 12/14/2022]
Abstract
Coordinated contractions of the smooth muscle layers of the gastrointestinal (GI) tract are required to produce motor patterns that ensure normal GI motility. The crucial role of the enteric nervous system (ENS), the intrinsic ganglionated network located within the GI wall, has long been recognized in the generation of the main motor patterns. However, devising an appropriate motility requires the integration of informations emanating from the lumen of the GI tract. As already found more than half a century ago, the ability of the GI tract to respond to mechanical forces such as stretch is not restricted to neuronal mechanisms. Instead, mechanosensitivity is now recognized as a property of several non-neuronal cell types, the excitability of which is probably involved in shaping the motor patterns. This brief review gives an overview on how mechanosensitivity of different cell types in the GI tract has been established and, whenever available, on what ionic conductances are involved in mechanotransduction and their potential impact on normal GI motility.
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Affiliation(s)
- Bruno Mazet
- Aix Marseille Université, CNRS, CRN2M UMR 7286, CS80011 Bd Pierre Dramard, 13344, Marseille Cedex 15, France,
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12
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Effects of a Hydrogen Sulfide Donor on Spontaneous Contractile Activity of Rat Stomach and Jejunum. Bull Exp Biol Med 2014; 157:302-6. [DOI: 10.1007/s10517-014-2551-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 01/28/2023]
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Abstract
BACKGROUND Interstitial cells of Cajal, expressing the proto-oncogene c-kit, have been shown to regulate the spontaneous activity of the gastrointestinal tract. They have been described in the human internal anal sphincter; however, their function is still unclear. OBJECTIVE We examined the effects of the c-kit tyrosine kinase inhibitor imatinib mesylate on sphincter strips to investigate the function of the interstitial cells. DESIGN This was a case series study. SETTIGS This was a single-center study conducted at the University of Oxford. PATIENTS Internal anal sphincter strips were collected from 10 patients undergoing abdominoperineal resection or proctectomy and mounted in organ bath. Responses to electrical field stimulation and chemical agents were monitored in the absence of drugs and after the administration of increasing doses of imatinib mesylate. Immunohistochemistry was performed to identify interstitial cells. MAIN OUTCOME MEASURES The role of the interstitial cells in the internal anal sphincter was assessed. RESULTS Imatinib mesylate significantly reduced the tone and the spontaneous activity of the strips. In the absence of drugs, the tone generated was 147.7 ± 33.0 mg/mg of tissue. Administration of ≥5 μM of imatinib mesylate caused a dose-dependent reduction in the tone. Strips exhibited spontaneous activity characterized by intermittent low-amplitude contractions superimposed on basal tone (135.6 ± 4.6 contractions in 10 minutes). Imatinib mesylate significantly reduced the number of contractions at concentration >5 μM. No differences were observed in the responses to electrical field stimulation, carbachol, or phenylephrine. Immunohistochemistry showed c-kit-positive cells. LIMITATIONS This study was limited by the relatively small number of patients enrolled and thus the difficulty of finding human tissue for laboratory studies. CONCLUSIONS Our results suggest that the interstitial cells modulate the tone and the spontaneous activity of the internal anal sphincter. This provides a foundation for new approaches to preclinical and clinical research. Moreover, these cells may represent a target for drugs inhibiting the c-kit receptor and provide a new approach for treating anorectal diseases.
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Chakrabarty B, Dey A, Lam M, Ventura S, Exintaris B. Tamsulosin modulates, but does not abolish the spontaneous activity in the guinea pig prostate gland. Neurourol Urodyn 2014; 34:482-8. [PMID: 24436088 DOI: 10.1002/nau.22557] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/13/2013] [Indexed: 11/12/2022]
Abstract
AIMS To examine the effects of the α1A -adrenoceptor antagonist, tamsulosin, on spontaneous contractile and electrical activity in the guinea-pig prostate gland. METHODS The effects of tamsulosin (0.1 and 0.3 nM) were investigated in adult and ageing male guinea pig prostate glands using conventional tension recording and electrophysiological intracellular microelectrode recording techniques. RESULTS Tamsulosin reduced spontaneous activity, and had different age-dependent effects on adult and ageing guinea pigs at different concentrations. 0.1 nM tamsulosin caused a significantly greater reduction of spontaneous contractile and electrical activity in ageing guinea pigs in comparison to adult guinea pigs. In contrast, 0.3 nM tamsulosin had a significantly greater reduction of spontaneous contractile and electrical activity in adult guinea pigs in comparison to ageing guinea pigs. CONCLUSIONS This study demonstrates that tamsulosin can modulate spontaneous myogenic stromal contractility and the underlying spontaneous electrical activity; tamsulosin does not block spontaneous activity. This reduction in spontaneous activity suggests that downstream cellular mechanisms underlying smooth muscle tone are being targeted, and these may represent novel therapeutic targets to better treat benign prostatic hyperplasia.
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Affiliation(s)
- Basu Chakrabarty
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria 3052, Australia
| | - Anupa Dey
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria 3052, Australia
| | - Michelle Lam
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria 3052, Australia
| | - Sabatino Ventura
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria 3052, Australia
| | - Betty Exintaris
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria 3052, Australia
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15
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Reverse mode of the sodium/calcium exchanger subtype 3 in interstitial cells of Cajal from rat bladder. Urology 2013; 82:254.e7-12. [PMID: 23688374 DOI: 10.1016/j.urology.2013.02.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Revised: 02/13/2013] [Accepted: 02/26/2013] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To investigate how the sodium/calcium exchanger subtype 3 (NCX3) and its reverse mode contribute to the function of interstitial cells of Cajal (ICCs) from the rat bladder. METHODS The study used 20 female Wistar rats. We observed the expression of the NCX3 expression in the bladder using reverse transcriptase-polymerase chain reaction and Western blotting. The NCX3 in ICCs was also confirmed by double-labeled fluorescence. NCX3 functions in reverse mode of ICCs were observed using confocal microscopy with preload fluo-3AM, and its currents were evaluated using the whole-cell patch clamp technique, with or without the NCX3 inhibitor KB-R7943 (5 and 30μM), with an afterward identification of ICCs using single-cell polymerase chain reaction. RESULTS NCX3 was confirmed in rat bladder ICCs. The time required for the intracellular calcium concentration [Ca(2+)]i of NCX3 was enhanced by KB-R7943 (5μM, P ≤.01). Moreover, KB-R7943 (5 and 30μM) significantly decreased the currents generated by the reverse mode of NCX3 from the ICCs (P <.05). CONCLUSION NCX3 is expressed in rat bladder ICCs. The reverse mode of NCX3 can generate [Ca(2+)]i of the bladder ICCs.
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16
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Chen JH, Zhang Q, Yu Y, Li K, Liao H, Jiang L, Hong L, Du X, Hu X, Chen S, Yin S, Gao Q, Yin X, Luo H, Huizinga JD. Neurogenic and myogenic properties of pan-colonic motor patterns and their spatiotemporal organization in rats. PLoS One 2013; 8:e60474. [PMID: 23577116 PMCID: PMC3618275 DOI: 10.1371/journal.pone.0060474] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 02/26/2013] [Indexed: 02/06/2023] Open
Abstract
Background and Aims Better understanding of intrinsic control mechanisms of colonic motility will lead to better treatment options for colonic dysmotility. The aim was to investigate neurogenic and myogenic control mechanisms underlying pan-colonic motor patterns. Methods Analysis of in vitro video recordings of whole rat colon motility was used to explore motor patterns and their spatiotemporal organizations and to identify mechanisms of neurogenic and myogenic control using pharmacological tools. Results Study of the pan-colonic spatiotemporal organization of motor patterns revealed: fluid-induced or spontaneous rhythmic propulsive long distance contractions (LDCs, 0.4–1.5/min, involving the whole colon), rhythmic propulsive motor complexes (RPMCs) (0.8–2.5/min, dominant in distal colon), ripples (10–14/min, dominant in proximal colon), segmentation and retrograde contractions (0.1–0.8/min, prominent in distal and mid colon). Spontaneous rhythmic LDCs were the dominant pattern, blocked by tetrodotoxin, lidocaine or blockers of cholinergic, nitrergic or serotonergic pathways. Change from propulsion to segmentation and distal retrograde contractions was most prominent after blocking 5-HT3 receptors. In the presence of all neural blockers, bethanechol consistently evoked rhythmic LDC-like propulsive contractions in the same frequency range as the LDCs, indicating the existence of myogenic mechanisms of initiation and propulsion. Conclusions Neurogenic and myogenic control systems orchestrate distinct and variable motor patterns at different regions of the pan-colon. Cholinergic, nitrergic and serotonergic pathways are essential for rhythmic LDCs to develop. Rhythmic motor patterns in presence of neural blockade indicate the involvement of myogenic control systems and suggest a role for the networks of interstitial cells of Cajal as pacemakers.
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Affiliation(s)
- Ji-Hong Chen
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University and Wuhan University Institute of Digestive and Liver Diseases, Wuhan, Hubei, China.
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Wang JP, Ding GF, Wang QZ. Interstitial cells of Cajal mediate excitatory sympathetic neurotransmission in guinea pig prostate. Cell Tissue Res 2013; 352:479-86. [PMID: 23411811 DOI: 10.1007/s00441-013-1572-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/17/2013] [Indexed: 01/26/2023]
Abstract
Morphological and functional studies have confirmed that interstitial cells of Cajal (ICCs) are involved in many enteric motor neurotransmission pathways. Recent investigations have demonstrated that human and guinea pig prostate glands possess a distinct cell type with morphological and immunological similarities to ICCs. These prostate ICCs have a close relationship with nerve bundles and smooth muscle cells. Prostate smooth muscle tone is largely induced by stimulation from the sympathetic nervous system, which releases excitatory norepinephrine (NE) to act on the α1-adrenoceptor. We have performed morphological and functional experiments to determine the role of ICCs in sympathetic neurotransmission in the guinea pig prostate based on the hypothesis that prostate ICCs act as mediators of sympathetic neurotransmission. Immunohistochemistry revealed many close points of contact between ICCs and sympathetic nerve bundles and smooth muscle cells. Double-labeled sections revealed that α1-adrenoceptor and the gap junction protein connexin 43 were expressed in prostate ICCs. Surprisingly, prostate ICCs co-expressed tyrosine hydroxylase and dopamine β-hydroxylase, two markers of sympathetic neurons. Functionally, the application of NE evoked a large single inward current in isolated prostate ICCs in a dose-dependent manner. The inward current evoked by NE was mediated via the activation of α1-adrenoceptors, because it was abolished by the non-specific α-adrenoceptor antagonist, phentolamine and the specific α1-adrenoceptor antagonist, prazosin. Thus, ICCs in the guinea pig prostate are target cells for prostate sympathetic nerves and possess the morphological and functional characteristics required to mediate sympathetic signals.
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Affiliation(s)
- Jiang-ping Wang
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
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Li S, Maude-Griffin R, Pullan AJ, Chen JDZ. Gastric emptying and Ca(2+) and K(+) channels of circular smooth muscle cells in diet-induced obese prone and resistant rats. Obesity (Silver Spring) 2013; 21:326-35. [PMID: 23404843 DOI: 10.1002/oby.20021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 06/18/2012] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Accelerated gastric emptying that precipitates hunger and frequent eating could be a potential factor in the development of obesity. The aim of this study was to study gastric emptying in diet-induced obese-prone (DIO-P) and DIO-resistant (DIO-R) rats and explore possible differences in electrical properties of calcium (Ca(2+) ) and potassium (K(+) ) channels of antral circular smooth muscle cells (SMCs). DESIGN AND METHODS Whole-cell patch-clamp technique was used to measure Ca(2+) and K(+) currents in single SMCs. Gastric emptying was evaluated 90 min after the ingestion of a solid meal. RESULTS Solid gastric emptying in the DIO-P rats was significantly faster compared with that in the DIO-R rats. The peak amplitude of L-type Ca(2+) current (IBa,L ) at 10 mV in DIO-P rats was greater than that in DIO-R rats without alternation of the current-voltage curve and voltage-dependent activation and inactivation. The half-maximal inactivation voltage of transient outward K(+) current (IKto ) was more depolarized (∼4 mV) in DIO-P rats compared with that in DIO-R rats. No difference was found in the current density or recovery kinetics of IKto between two groups. The current density of delayed rectifier K(+) current (IKdr ), which was sensitive to tetraethylammonium chloride but not 4-aminopyridine, was lower in DIO-P rats than that in DIO-R rats. CONCLUSION The accelerated gastric emptying in DIO-P rats might be attributed to a higher density of IBa,L , depolarizing shift of inactivation curve of IKto and lower density of IKdr observed in the antral SMCs of DIO-P rats.
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Affiliation(s)
- Shiying Li
- Veterans Research and Education Foundation, VA Medical Center, Oklahoma, Oklahoma, USA
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Somarajan S, Cassilly S, Obioha C, Bradshaw LA, Richards WO. Noninvasive biomagnetic detection of isolated ischemic bowel segments. IEEE Trans Biomed Eng 2013; 60:1677-84. [PMID: 23335661 DOI: 10.1109/tbme.2013.2240454] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The slow wave activity was measured in the magnetoenterogram (MENG) of normal porcine subjects (N = 5) with segmental intestinal ischemia. The correlation changes in enteric slow wave activity were determined in MENG and serosal electromyograms (EMG). MENG recordings show significant changes in the frequency and power distribution of enteric slow-wave signals during segmental ischemia, and these changes agree with changes observed in the serosal EMG. There was a high degree of correlation between the frequency of the electrical activity recorded in MENG and in serosal EMG (r = 0.97). The percentage of power distributed in brady- and normoenteric frequency ranges exhibited significant segmental ischemic changes. Our results suggest that noninvasive MENG detects ischemic changes in isolated small bowel segments.
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Affiliation(s)
- Suseela Somarajan
- Department of General Surgery and Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA.
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20
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Ball ER, Matsuda MM, Dye L, Hoffmann V, Zerfas PM, Szarek E, Rich A, Chitnis AB, Stratakis CA. Ultra-structural identification of interstitial cells of Cajal in the zebrafish Danio rerio. Cell Tissue Res 2012; 349:483-91. [PMID: 22628160 PMCID: PMC3674513 DOI: 10.1007/s00441-012-1434-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 04/12/2012] [Indexed: 11/27/2022]
Abstract
The interstitial cells of Cajal (ICCs) are important mediators of gastrointestinal (GI) motility because of their role as pacemakers in the GI tract. In addition to their function, ICCs are also structurally distinct cells most easily identified by their ultra-structural features and expression of the tyrosine kinase receptor c-KIT. ICCs have been described in mammals, rodents, birds, reptiles, and amphibians, but there are no reports at the ultra-structural level of ICCs within the GI tract of an organism from the teleost lineage. We describe the presence of cells in the muscularis of the zebrafish intestine; these cells have similar features to ICCs in other vertebrates. The ICC-like cells are associated with the muscularis, are more electron-dense than surrounding smooth muscle cells, possess long cytoplasmic processes and mitochondria, and are situated opposing enteric nervous structures. In addition, immunofluorescent and immunoelectron-microscopic studies with antibodies targeting the zebrafish ortholog of a putative ICC marker, c-KIT (kita), showed c-kit immunoreactivity in zebrafish ICCs. Taken together, these data represent the first ultra-structural characterization of cells in the muscularis of the zebrafish Danio rerio and suggest that ICC differentiation in vertebrate evolution dates back to the teleost lineage.
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Affiliation(s)
- Evan R Ball
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 10, CRC, Room 1-3330, 10 Center Drive, MSC1103, Bethesda, MD 20892, USA
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FINTL C, PEARSON GT, MAYHEW IG, HUDSON NPH. In vitro electrical activity of the equine pelvic flexure. Equine Vet J 2011:145-8. [DOI: 10.1111/j.2042-3306.2011.00396.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Perrino BA. Regulation of gastrointestinal motility by Ca2+/calmodulin-stimulated protein kinase II. Arch Biochem Biophys 2011; 510:174-81. [PMID: 21443856 DOI: 10.1016/j.abb.2011.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 03/15/2011] [Accepted: 03/21/2011] [Indexed: 12/30/2022]
Abstract
Gastrointestinal (GI) motility ultimately depends upon the contractile activity of the smooth muscle cells of the tunica muscularis. Integrated functioning of multiple tissues and cell types, including enteric neurons and interstitial cells of Cajal (ICC) is necessary to generate coordinated patterns of motor activity that control the movement of material through the digestive tract. The neurogenic mechanisms that govern GI motility patterns are superimposed upon intrinsic myogenic mechanisms regulating smooth muscle cell excitability. Several mechanisms regulate smooth muscle cell responses to neurogenic inputs, including the multifunctional Ca(2+)/calmodulin-stimulated protein kinase II (CaMKII). CaMKII can be activated by Ca(2+) transients from both extracellular and intracellular sources. Prolonging the activities of Ca(2+)-sensitive K(+) channels in the plasma membrane of GI smooth muscle cells is an important regulatory mechanism carried out by CaMKII. Phospholamban (PLN) phosphorylation by CaMKII activates the sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA), increasing both the rate of Ca(2+) clearance from the myoplasm and the frequency of localized Ca(2+) release events from intracellular stores. Overall, CaMKII appears to moderate GI smooth muscle cell excitability. Finally, transcription factor activities may be facilitated by the neutralization of HDAC4 by CaMKII phosphorylation, which may contribute to the phenotypic plasticity of GI smooth muscle cells.
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Affiliation(s)
- Brian A Perrino
- Department of Physiology and Cell Biology, Center of Biomedical Research Excellence, University of Nevada School of Medicine, Reno, 89557, USA.
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Dey A, Kusljic S, Lang RJ, Exintaris B. Role of connexin 43 in the maintenance of spontaneous activity in the guinea pig prostate gland. Br J Pharmacol 2011; 161:1692-707. [PMID: 20735413 DOI: 10.1111/j.1476-5381.2010.01001.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE To investigate the role of connexin 43 in the maintenance of spontaneous activity in prostate tissue from young and old guinea pigs. EXPERIMENTAL APPROACH Conventional intracellular microelectrode and tension recording techniques, coupled with Western blot analysis and immunohistochemistry for connexin 43 (CX43) were used. The effects of three gap junction uncouplers, 18β glycyrrhetinic acid (10 µM, 40 µM), carbenoxolone (10 µM, 50 µM) and octanol (0.5 mM, 1 mM), were studied in cells displaying slow wave activity and on spontaneously contracting tissue from prostate glands of young (2-5 months) and old (9-16 months) guinea pigs. KEY RESULTS 18β Glycyrrhetinic acid (40 µM), carbenoxolone (50 µM) or octanol (0.5 mM) abolished slow wave activity in prostate tissue from young and old guinea pigs and depolarized membrane potential by approximately 5 mV. These treatments also abolished all contractions in both sets of prostate tissue. These effects were reversed upon washout. Western blot analysis and CX43 immunohistochemistry showed that there was no age-related difference in the expression and distribution of CX43 in prostate tissues. CONCLUSION AND IMPLICATIONS When gap junctional communication via CX43 was disrupted, spontaneous activity was abolished at a cellular and whole tissue level; CX43 is therefore essential for the maintenance of spontaneous slow wave activity and subsequent contractile activity in the guinea pig prostate gland.
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Affiliation(s)
- Anupa Dey
- Medicinal Chemistry & Drug Action, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
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Nguyen DTT, Dey A, Lang RJ, Ventura S, Exintaris B. Contractility and pacemaker cells in the prostate gland. J Urol 2011; 185:347-51. [PMID: 21075393 DOI: 10.1016/j.juro.2010.09.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Indexed: 11/27/2022]
Abstract
PURPOSE We focused on the current opinion on mechanisms generating stromal tone in the prostate gland. MATERIALS AND METHODS We selected the guinea pig as the main species for investigation since its prostate has a high proportion of smooth muscle that undergoes age related changes similar in many respects to that in humans. The main techniques that we used were tension recording and electrophysiology. RESULTS We previously reported distinct electrical activity and cell types in the prostate, and speculated on their functional roles. We believe that a specialized group of c-kit immunoreactive prostatic interstitial cells that lie between glandular epithelium and smooth muscle stroma have a role similar to that of gastrointestinal interstitial cells of Cajal, generating the pacemaker signal that manifests as slow wave activity and triggers contraction in smooth muscle cells in guinea pig prostates. CONCLUSIONS Since changes in muscle tone are involved in the etiology of age dependent prostate specific conditions such as benign prostatic hyperplasia, knowledge of the electrical properties of the various prostatic cell types and their interactions with each other, with nerves and with the hormonal environment, and how these factors change with age is of considerable medical importance.
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Affiliation(s)
- Dan-Thanh T Nguyen
- Monash Institute of Pharmaceutical Sciences, Parkville and Department of Physiology, Monash University, Clayton, Victoria, Australia
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Abstract
The study of novel interstitial cells in the tissues of the urinary tract has defined advances in the field in the last decade. These intriguing cells belong to the same family as the better known interstitial cells of Cajal (ICC) of the gastrointestinal tract, and their discovery has been interpreted to suggest that pacemaker cells may be present in the urinary tract, driving the spontaneous or myogenic activity of the neighboring smooth muscle. This scenario may be true for the urethra where ICC have been described as "loose pacemakers" providing multiple, random inputs to modulate urethral smooth muscle activity. However, there is a paucity of direct evidence available to support this hypothesis in the bladder (where the smooth muscle cells are spontaneously active) or the renal pelvis (where atypical smooth muscle cells are the pacemakers), and it now seems more likely that urinary tract ICC act as modulators of smooth muscle activity.Interestingly, the literature suggests that the role of urinary tract ICC may be more apparent in pathophysiological conditions such as the overactive bladder. Several reports have indicated that the numbers of ICC present in overactive bladder tissues are greater than those from normal tissues; moreover, the contractility of tissues from overactive bladders in vitro appears to be more sensitive to the Kit antagonist, glivec, than those from normal bladder. Future research on urinary tract ICC in the short to medium term is likely to be dynamic and exciting and will lead to increasing our understanding of the roles of these cells in both normal and dysfunctional bladder.
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Affiliation(s)
- Karen D McCloskey
- School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK.
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Fintl C, Hudson NPH. The interstitial cells of Cajal of the equine gastrointestinal tract: what we know so far. Equine Vet J 2010; 42:372-7. [PMID: 20525058 DOI: 10.1111/j.2042-3306.2010.00073.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gastrointestinal motility disorders are a serious problem in both veterinary and human medicine and may represent a dysfunction of the neural, muscular or pacemaker components (interstitial cells of Cajal) of bowel control. The interstitial cells of Cajal are considered to be the pacemakers and mediators of certain forms of neurotransmission in the gastrointestinal tract. These cells have been implicated, either primarily or secondarily, in the pathogenesis of gastrointestinal disease processes in which there is a prominent element of disturbance to intestinal motility. In the horse, their involvement has been implicated in large intestinal obstructive colic and grass sickness (equine dysautonomia). This review highlights the properties of the interstitial cells of Cajal and the role these cells play in orchestrating gastrointestinal motility patterns. In addition, it examines their role in intestinal motility disorders and summarises our current understanding of their importance in the equine gastrointestinal tract.
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Affiliation(s)
- C Fintl
- Norwegian School of Veterinary Science, Department of Companion Animal Clinical Sciences, PO Box 8146 Dep., 0033 Oslo, Norway
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McCloskey KD. Interstitial cells in the urinary bladder--localization and function. Neurourol Urodyn 2010; 29:82-7. [PMID: 20025023 DOI: 10.1002/nau.20739] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AIMS This review summarizes the currently available literature on the localization and proposed functions of a novel group of cells in the urinary bladder known as interstitial cells or interstitial cells of Cajal (ICC). METHODS On-line searches of "Pubmed" for bladder, c-Kit, ICC, interstitial cell and myofibroblast were performed to identify relevant studies for the review. RESULTS The literature contains substantial data that several sub-populations of ICC are present in the wall of the mammalian urinary bladder. These are located in the lamina propria and within the detrusor with distinctive cell shapes and morphological arrangements. Bladder ICC are identified with transmission electron microscopy or by immunohistochemical labeling using antibodies to the Kit receptor which is an established ICC marker. Lamina propria-ICC form a loose network connected via Cx43 gap junctions and are associated with mucosal nerves. Detrusor ICC track the smooth muscle bundles and make frequent contacts with intramural nerves. Both groups of ICC exhibit spontaneous electrical and Ca2+-signalling and also respond to application of neurotransmitter substances including ATP and carbachol. There is emerging evidence that the expression of ICC is upregulated in pathophysiological conditions including the overactive bladder. CONCLUSIONS There is now a convincing body of evidence that specialized ICC are present in the urinary bladder making important associations with other cells that make up the bladder wall and possessing physiological properties consistent with a role of bladder activity modulation.
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Affiliation(s)
- Karen D McCloskey
- School of Medicine, Dentistry and Biomedical Sciences, Medical Biology Centre, Belfast, Northern Ireland, UK.
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Park SY, Je HD, Shim JH, Sohn UD. Characteristics of spontaneous contraction in the circular smooth muscles of cat ileum. Arch Pharm Res 2010; 33:159-65. [DOI: 10.1007/s12272-010-2238-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/27/2009] [Accepted: 11/16/2009] [Indexed: 12/01/2022]
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Ye-Lin Y, Garcia-Casado J, Martinez-de-Juan JL, Prats-Boluda G, Ponce JL. The detection of intestinal spike activity on surface electroenterograms. Phys Med Biol 2010; 55:663-80. [PMID: 20071756 DOI: 10.1088/0031-9155/55/3/008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Myoelectrical recording could provide an alternative technique for assessing intestinal motility, which is a topic of great interest in gastroenterology since many gastrointestinal disorders are associated with intestinal dysmotility. The pacemaker activity (slow wave, SW) of the electroenterogram (EEnG) has been detected in abdominal surface recordings, although the activity related to bowel contractions (spike bursts, SB) has to date only been detected in experimental models with artificially favored electrical conductivity. The aim of the present work was to assess the possibility of detecting SB activity in abdominal surface recordings under physiological conditions. For this purpose, 11 recording sessions of simultaneous internal and external myolectrical signals were conducted on conscious dogs. Signal analysis was carried out in the spectral domain. The results show that in periods of intestinal contractile activity, high-frequency components of EEnG signals can be detected on the abdominal surface in addition to SW activity. The energy between 2 and 20 Hz of the surface myoelectrical recording presented good correlation with the internal intestinal motility index (0.64 +/- 0.10 for channel 1 and 0.57 +/- 0.11 for channel 2). This suggests that SB activity can also be detected in canine surface EEnG recording.
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Affiliation(s)
- Y Ye-Lin
- Instituto interuniversitario de investigación en bioingeniería y tecnología orientada al ser humano (I3BH),Universidad Politécnica de Valencia, Camino de Vera, s/n, Ed. 8E, Acceso N, 2a, planta 46022 Valencia, Spain.
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Sun Y, Song GQ, Yin J, Lei Y, Chen JDZ. Effects and mechanisms of gastrointestinal electrical stimulation on slow waves: a systematic canine study. Am J Physiol Regul Integr Comp Physiol 2009; 297:R1392-9. [PMID: 19710395 DOI: 10.1152/ajpregu.00006.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The aims of this study were to determine optimal pacing parameters of electrical stimulation on different gut segments and to investigate effects and possible mechanisms of gastrointestinal electrical stimulation on gut slow waves. Twelve female hound-mix dogs were used in this study. A total of six pairs of electrodes were implanted on the stomach, duodenum, and ascending colon. Bilateral truncal vagotomy was performed in six of the dogs. One experiment was designed to study the effects of the pacing frequency on the entrainment of gut slow waves. Another experiment was designed to study the modulatory effects of the vagal and sympathetic pathways on gastrointestinal pacing. The frequency of slow waves was 4.88 +/- 0.23 cpm (range, 4-6 cpm) in the stomach and 19.68 +/- 0.31 cpm (range, 18-22 cpm) in the duodenum. There were no consistent or dominant frequencies of the slow waves in the colon. The optimal parameters to entrain slow waves were: frequency of 1.1 intrinsic frequency (IF; 10% higher than IF) and pulse width of 150-450 ms (mean, 320.0 +/- 85.4 ms) for the stomach, and 1.1 IF and 10-20 ms for the small intestine. Electrical stimulation was not able to alter colon slow waves. The maximum entrainable frequency was 1.27 IF in the stomach and 1.21 IF in the duodenum. Gastrointestinal pacing was not blocked by vagotomy nor the application of an alpha- or beta-adrenergic receptor antagonist; whereas the induction of gastric dysrhythmia with electrical stimulation was completely blocked by the application of the alpha- or beta-adrenergic receptor antagonist. Gastrointestinal pacing is achievable in the stomach and small intestine but not the colon, and the maximal entrainable frequency of the gastric and small intestinal slow waves is about 20% higher than the IF. The entrainment of slow waves with gastrointestinal pacing is not modulated by the vagal or sympathetic pathways, suggesting a purely peripheral or muscle effect.
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Affiliation(s)
- Yan Sun
- Veterans Research and Education Foundation, Veterans Affairs Medical Center, Oklahoma City, Oklahoma 73104, USA
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Jepps TA, Greenwood IA, Moffatt JD, Sanders KM, Ohya S. Molecular and functional characterization of Kv7 K+ channel in murine gastrointestinal smooth muscles. Am J Physiol Gastrointest Liver Physiol 2009; 297:G107-15. [PMID: 19389803 PMCID: PMC2711751 DOI: 10.1152/ajpgi.00057.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Members of the K(v)7 voltage-gated K(+) channel family are important determinants of cardiac and neuronal membrane excitability. Recently, we and others have shown that K(v)7 channels are also crucial regulators of smooth muscle activity. The aim of the present study was to assess the K(v)7 expression in different parts of the murine gastrointestinal (GI) tract and to assess their functional roles by use of pharmacological agents. Of KCNQ/K(v)7 members, both KCNQ4/K(v)7.4 and KCNQ5/K(v)7.5 genes and proteins were the most abundantly expressed K(v)7 channels in smooth muscles throughout the GI tract. Immunohistochemical staining also revealed that K(v)7.4 and K(v)7.5 but not K(v)7.1 were expressed in the circular muscle layer of the colon. In segments of distal colon circular muscle exhibiting spontaneous phasic contractions, the nonselective K(v)7 blockers XE991 and linopirdine increased the integral of tension. Increases in the integral of tension were also observed under conditions of neuronal blockade. Similar effects, although less marked, were observed in the proximal colon. As expected, the K(v)7.1-selective blocker chromanol 293B had no effect in either type of segment. These data show that K(v)7.x especially K(v)7.4 and K(v)7.5 are expressed in different regions of the murine gastrointestinal tract and blockers of K(v)7 channels augment inherent contractile activity. Drugs that selectively block K(v)7.4/7.5 might be promising therapeutics for the treatment of motility disorders such as constipation associated with irritable bowel syndrome.
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Affiliation(s)
- Thomas A. Jepps
- Division of Basic Medical Sciences, St George's, University of London, London, United Kingdom; Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Iain A. Greenwood
- Division of Basic Medical Sciences, St George's, University of London, London, United Kingdom; Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - James D. Moffatt
- Division of Basic Medical Sciences, St George's, University of London, London, United Kingdom; Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Kenton M. Sanders
- Division of Basic Medical Sciences, St George's, University of London, London, United Kingdom; Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Susumu Ohya
- Division of Basic Medical Sciences, St George's, University of London, London, United Kingdom; Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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Owyang C. Recent advances and future research directions in neurogastroenterology and endocrinology recommendations of the National Commission on Digestive Diseases. Neurogastroenterol Motil 2008; 20:1189-203. [PMID: 19019020 DOI: 10.1111/j.1365-2982.2008.01212.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Recently, a draft of the report of the National Commission on Digestive Diseases was made available to the public. The Commission was given the task of assessing the current state of science in digestive diseases research, and developing a 10-year plan for digestive diseases research consistent with National Institutes of Health (NIH)'s mission of improving the health of the nation through research. Twelve topic-specific areas were selected for organizing the content of the long-range research plan. One chapter was devoted to Research on the Basic Biology of the Digestive System covering major biological pathways which regulate the physiology and biochemistry of the gastrointestinal tract. The author wrote about the areas related to neurogastroenterology, endocrinology and satiety. In this communication, recent advances in these areas are reviewed and major recommendations for future research endeavours are highlighted. Collectively, the recommendations will provide scientific direction for the NIH and all parties engaged in digestive disease research as they address opportunities in digestive diseases research over the next decade.
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Affiliation(s)
- C Owyang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-5362, USA.
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Kaufmann C, Keller C, Oevermann A, Steiner A, Hirsbrunner G. Spontaneous contractility of bovine myometrium in vitro depending on topography and cycle phase. Theriogenology 2008; 70:880-6. [DOI: 10.1016/j.theriogenology.2008.05.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2008] [Revised: 05/08/2008] [Accepted: 05/08/2008] [Indexed: 11/29/2022]
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Kim M, Hennig GW, Park K, Han IS, Smith TK, Koh SD, Perrino BA. Modulation of murine gastric antrum smooth muscle STOC activity and excitability by phospholamban. J Physiol 2008; 586:4977-91. [PMID: 18755751 DOI: 10.1113/jphysiol.2008.156836] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We investigated intracellular Ca(2+) waves, spontaneous transient outward currents (STOCs), and membrane potentials of gastric antrum smooth muscle cells from wild-type and phospholamban-knockout mice. The NO donor sodium nitroprusside (SNP) increased intracellular Ca(2+) wave activity in wild-type antrum smooth muscle cells, but had no effect on the constitutively elevated intracellular Ca(2+) wave activity of phospholamban-knockout cells. STOC activity was also constitutively elevated in phospholamban-knockout antrum smooth muscle cells relative to wild-type cells. SNP or 8-bromo-cGMP increased the STOC activity of wild-type antrum smooth muscle cells, but had no effect on STOC activity of phospholamban-knockout cells. Iberiotoxin, but not apamin, inhibited STOC activity in wild-type and phospholamban-knockout antrum smooth muscle cells. In the presence of SNP, STOC activity in wild-type and phospholamban-knockout antrum smooth muscle cells was inhibited by ryanodine, but not 2-APB. The cGMP-dependent protein kinase inhibitor KT5823 reversed the increase in STOC activity evoked by SNP in wild-type antrum smooth muscle cells, but had no effect on STOC activity in phospholamban-knockout cells. The resting membrane potential of phospholamban-knockout antrum smooth muscle cells was hyperpolarized by approximately -6 mV compared to wild-type cells. SNP hyperpolarized the resting membrane potential of wild-type antrum smooth muscle cells to a greater extent than phospholamban-knockout antrum smooth muscles. Despite the hyperpolarized membrane potential, slow wave activity was significantly increased in phospholamban-knockout antrum smooth muscles compared to wild-type smooth muscles. These results suggest that phospholamban is an important component of the mechanisms regulating the electrical properties of gastric antrum smooth muscles.
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Affiliation(s)
- Minkyung Kim
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Myosin light chain kinase is central to smooth muscle contraction and required for gastrointestinal motility in mice. Gastroenterology 2008; 135:610-20. [PMID: 18586037 PMCID: PMC2648853 DOI: 10.1053/j.gastro.2008.05.032] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 04/24/2008] [Accepted: 05/08/2008] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Smooth muscle is essential for maintaining homeostasis for many body functions and provides adaptive responses to stresses imposed by pathologic disorders. Identified cell signaling networks have defined many potential mechanisms for initiating smooth muscle contraction with or without myosin regulatory light chain (RLC) phosphorylation by myosin light chain kinase (MLCK). We generated tamoxifen-inducible and smooth muscle-specific MLCK knockout (KO) mice and provide direct loss-of-function evidence that shows the primary importance of MLCK in phasic smooth muscle contractions. METHODS We used the Cre-loxP system to establish Mlck floxed mice in which exons 23, 24, and 25 were flanked by 2 loxP sites. Smooth muscle-specific MLCK KO mice were generated by crossing Mlck floxed mice with SM-CreER(T2) (ki) mice followed by tamoxifen treatment. The phenotype was assessed by histologic, biochemical, molecular, cell biological, and physiologic analyses. RESULTS Targeted deletion of MLCK in adult mouse smooth muscle resulted in severe gut dysmotility characterized by weak peristalsis, dilation of the digestive tract, and reduction of feces excretion and food intake. There was also abnormal urinary bladder function and lower blood pressure. Isolated muscles showed a loss of RLC phosphorylation and force development induced by K(+)-depolarization. The kinase knockout also markedly reduced RLC phosphorylation and force development with acetylcholine which activates Ca(2+)-sensitizing signaling pathways. CONCLUSIONS MLCK and its phosphorylation of RLC are required physiologically for smooth muscle contraction and are essential for normal gastrointestinal motility.
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Bursian AV. Organization and development of pacemaker of the gastrointestinal tract. J EVOL BIOCHEM PHYS+ 2008. [DOI: 10.1134/s0022093008020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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37
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Clemente CM, Araújo PV, Palheta RC, Ratts ZML, Fernandes GH, Rola FH, de Oliveira RB, dos Santos AA, Magalhães PJC. Sildenafil inhibits duodenal contractility via activation of the NO-K+ channel pathway. Fundam Clin Pharmacol 2008; 22:61-7. [PMID: 18251723 DOI: 10.1111/j.1472-8206.2007.00549.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phosphodiesterase type-5 (PDE5) specifically cleaves cyclic guanosine monophosphate (cGMP), a key intracellular secondary messenger. The PDE5 inhibitor sildenafil is a well-known vasodilator that also has gastrointestinal myorelaxant properties. In the present study, we further investigated sildenafil-induced myorelaxation in rat isolated duodenum, assessing its interaction with nitric oxide (NO) synthase and K(+) channel opening. The spontaneous contractions of duodenal strips were reversibly inhibited by sildenafil (0.1-300 microM) in a concentration-dependent manner [mean (95% confidence interval); EC(50) = 6.8 (2.7-17.3) microM]. The sildenafil-induced myorelaxation was significantly decreased by the NO synthase inhibitor N-nitro-L-arginine methyl ester [increasing the EC(50) value to 41.9 (26.1-67.3) microM]. Sodium nitroprusside or forskolin pretreatments enhanced the sildenafil-induced myorelaxation. In isolated strips pretreated with BaCl(2) (0.2 mM), 4-aminopyridine (4-AP, 3 mM), or glybenclamide (1 microM), the sildenafil-induced EC(50) value was significantly increased to 32.8 (19.1-56.4), 27.1 (15.2-48.3) and 20.1 (16.4-24.7) microM, respectively. Minoxidil (50 microM) or diazoxide (100 microM) also significantly attenuated the sildenafil-induced potency. In conclusion, the NO synthase/cyclic nucleotide pathway activation is involved in sildenafil-induced inhibition of spontaneous duodenal contractions. Its pharmacological action seems to be influenced by K(+) channel opening, especially the voltage-sensitive ones, being inhibited by 4-AP and K(ATP) channels, sensitive to glybenclamide.
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Affiliation(s)
- Cristiano M Clemente
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE, Brazil
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Zhu Y, Huizinga JD. Nitric oxide decreases the excitability of interstitial cells of Cajal through activation of the BK channel. J Cell Mol Med 2008; 12:1718-27. [PMID: 18194464 PMCID: PMC3918088 DOI: 10.1111/j.1582-4934.2008.00217.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Nitrergic nerves are structurally and functionally associated with ICC. To further understand mechanisms of communication, the hypothesis was investigated that NO might affect large conductance K channels. To that end, we searched for IbTX-sensitive currents in ICC obtained through explant cultures from the mouse small intestine and studied effects of the NOS inhibitor omega N-nitro-L-arginine (LNNA) and the NO donor sodium nitroprusside (SNP). IbTX-sensitive currents acquired in the whole-cell configuration through nystatin perforated patches exhibited high noise levels but relatively low amplitude, whereas currents obtained in the conventional whole-cell configuration exhibited less noise and higher amplitudes; depolarization from -80 to + 40 mV evoked 357 +/- 159 pA current in the nystatin perforated patch configuration and 1075 +/- 597 pA using the conventional whole-cell configuration. Immunohistochemistry showed that ICC associated with ganglia and Auerbach's plexus nerve fibers were immunoreactive to BK antibodies. The IbTX-sensitive currents were increased by SNP and inhibited by LNNA. BK blockers suppressed spontaneous transit outward currents in ICC. After block of BK currents, or before these currents became prominent, calcium currents were activated by depolarization in the same cells. Their peak amplitude occurred at -25 mV and the currents were increased with increasing extracellular calcium and inhibited by cobalt. The hypothesis is warranted that nitrergic innervation inhibits ICC excitability in part through activation of BK channels. In addition, NO is an intracellular regulator of ICC excitability.
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Affiliation(s)
- Yaohui Zhu
- McMaster University, Intestinal Disease Research Programme, Department of Medicine, Hamilton, Ontario, Canada
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Johnston L, Carson C, Lyons AD, Davidson RA, McCloskey KD. Cholinergic-induced Ca2+ signaling in interstitial cells of Cajal from the guinea pig bladder. Am J Physiol Renal Physiol 2008; 294:F645-55. [PMID: 18171995 PMCID: PMC2640952 DOI: 10.1152/ajprenal.00526.2007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Acetylcholine released from parasympathetic excitatory nerves activates contraction in detrusor smooth muscle. Immunohistochemical labeling of guinea pig detrusor with anti-c-Kit and anti-VAChT demonstrated a close structural relationship between interstitial cells of Cajal (ICC) and cholinergic nerves. The ability of guinea pig bladder detrusor ICC to respond to the acetylcholine analog, carbachol, was investigated in enzymatically dissociated cells, loaded with the Ca2+ indicator fluo 4AM. ICC fired Ca2+ transients in response to stimulation by carbachol (1/10 μM). Their pharmacology was consistent with carbachol-induced contractions in strips of detrusor which were inhibited by 4-DAMP (1 μM), an M3 receptor antagonist, but not by the M2 receptor antagonist methoctramine (1 μM). The source of Ca2+ underlying the carbachol transients in isolated ICC was investigated using agents to interfere with influx or release from intracellular stores. Nifedipine (1 μM) or Ni2+ (30–100 μM) to block Ca2+ channels or the removal of external Ca2+ reduced the amplitude of the carbachol transients. Application of ryanodine (30 μM) or tetracaine (100 μM) abolished the transients. The phospholipase C inhibitor, U-73122 (2.5 μM), significantly reduced the responses. 2-Aminoethoxydiethylborate (30 μM) caused a significant reduction and Xestospongin C (1 μM) was more effective, almost abolishing the responses. Intact in situ preparations of guinea pig bladder loaded with a Ca2+ indicator showed distinctively different patterns of spontaneous Ca2+ events in smooth muscle cells and ICC. Both cell types responded to carbachol by an increase in frequency of these events. In conclusion, guinea pig bladder detrusor ICC, both as isolated cells and within whole tissue preparations, respond to cholinergic stimulation by firing Ca2+ transients.
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Affiliation(s)
- Louise Johnston
- Physiology, Division of Basic Medical Sciences, Medical Biology Centre, Belfast, Northern Ireland, UK BT9 7BL
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40
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Bayguinov O, Ward SM, Kenyon JL, Sanders KM. Voltage-gated Ca2+ currents are necessary for slow-wave propagation in the canine gastric antrum. Am J Physiol Cell Physiol 2007; 293:C1645-59. [PMID: 17855773 DOI: 10.1152/ajpcell.00165.2007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electrical slow waves determine the timing and force of peristaltic contractions in the stomach. Slow waves originate from a dominant pacemaker in the orad corpus and propagate actively around and down the stomach to the pylorus. The mechanism of slow-wave propagation is controversial. We tested whether Ca(2+) entry via a voltage-dependent, dihydropyridine-resistant Ca(2+) conductance is necessary for active propagation in canine gastric antral muscles. Muscle strips cut parallel to the circular muscle were studied with intracellular electrophysiological techniques using a partitioned-chamber apparatus. Slow-wave upstroke velocity and plateau amplitude decreased from the greater to the lesser curvature, and this corresponded to a decrease in the density of interstitial cells of Cajal in the lesser curvature. Slow-wave propagation velocity between electrodes impaling cells in two regions of muscle and slow-wave upstroke and plateau were measured in response to experimental conditions that reduce the driving force for Ca(2+) entry or block voltage-dependent Ca(2+) currents. Nicardipine (0.1-1 microM) did not affect slow-wave upstroke or propagation velocities. Upstroke velocity, amplitude, and propagation velocity were reduced in a concentration-dependent manner by Ni(2+) (1-100 microM), mibefradil (10-30 microM), and reduced extracellular Ca(2+) (0.5-1.5 mM). Depolarization (by 10-15 mM K(+)) or hyperpolarization (10 microM pinacidil) also reduced upstroke and propagation velocities. The higher concentrations (or lowest Ca(2+)) of these drugs and ionic conditions tested blocked slow-wave propagation. Treatment with cyclopiazonic acid to empty Ca(2+) stores did not affect propagation. These experiments show that voltage-dependent Ca(2+) entry is obligatory for the upstroke phase of slow waves and active propagation.
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Affiliation(s)
- Orline Bayguinov
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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41
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Zhang Y, Piao LH, Huang X, Han YF, Zhao P, Gao L, Kim Y, Xu WX. Pacemaker currents modulated by C-type natriuretic peptide in interstitial cells of cajal from murine small intestine. J Physiol Biochem 2007; 62:281-91. [PMID: 17615954 DOI: 10.1007/bf03165757] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although the presence of C-type natriuretic peptide (CNP) in gastrointestinal tract has been demonstrated, the effect of CNP on interstitial cells of Cajal (ICC), pacemaker cells in gastrointestinal tract, is still unclear. This study was designed to investigate the effect of CNP on pacemaker currents of ICC and possible mechanisms. We used immunocytochemistry techniques to exhibit natriuretic peptide receptors (NPR) and recorded membrane currents by using whole-cell patch clamp technique on cultured ICC. Our experiment showed that NPR-A and NPR-B were expressed in ICC from murine small intestine. Whole cell recordings further showed that the amplitude of pacemaker currents in intestinal small networks of ICC was 322+/-22pA and the frequency was 16.25+/-0.95Hz. CNP significantly reduced the amplitude of pacemaker currents in small networks of ICC in a dose-dependent manner, and the amplitude was inhibited by 23.95%, 61.76% and 81.67%, the amplitude values in 329+/-28.0pA, 311.2+/-14.8pA and 295+/-26.5pA before treatment with CNP and 237.9+/-27.5pA, 119.6+/-18.5pA and 57.2+/-13.5pA after treatment with 0.01 micromolxL(-1), 0.1 micromolxL(-1) and 1pmolxL(-1) CNP, respectively. The frequencies of pacemaker currents were also significantly reduced from 16.25+/-0.95Hz of control to 13+/-0.9Hz, 12+/-0.8Hz and 3+/-0.2Hz by 0.01micromolxL 1, 0.1micromolxL(-1) and 1 micromol x L(-1) CNP, respectively. CNP also inhibited the amplitude of pacemaker currents in single ICC. The inhibitory effect of CNP was mimicked by 8-Br-cGMP, a membrane permeable cGMP analogue, which suggests that CNP could inhibit pacemaker currents via NPR-B-particulate guanylate cyclase (pGC)-cGMP signal pathway.
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Affiliation(s)
- Y Zhang
- Department of Physiology, Medical College, Shanghai Jiaotong University, Shanghai 200240, China
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42
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Lyons AD, Gardiner TA, McCloskey KD. Kit-positive interstitial cells in the rabbit urethra: structural relationships with nerves and smooth muscle. BJU Int 2007; 99:687-94. [PMID: 17212607 DOI: 10.1111/j.1464-410x.2006.06617.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE To identify interstitial cells (ICs) in the wall of the rabbit urethra using antibodies to the Kit receptor, and to examine their location, morphology and relationship with nerves and smooth muscle cells (SMCs), as studies of enzymatically isolated cells from the rabbit urethra have established that there are specialized cells that show spontaneous electrical activity and have morphological properties of ICs. MATERIALS AND METHODS Urethral tissues from rabbits were fixed, labelled with antibodies and examined with confocal microscopy. Some specimens were embedded in paraffin wax and processed for histology. Histological sections from the most proximal third and mid-third region of rabbit urethra were stained with Masson's Trichrome to show their cellular arrangement. RESULTS Sections from both regions had outer longitudinal and inner circular layers of SM, and a lamina propria containing connective tissue and blood vessels; the lumen was lined with urothelial cells. The mid-third region had a more developed circular SM layer than the most-proximal samples, and had extensive inner longitudinal SM bundles in the lamina propria. Labelling with anti-Kit revealed immunopositive cells within the wall of the rabbit urethra, in the circular and longitudinal layers of the muscularis. Double-labelling with an antibody to SM myosin showed Kit-positive cells on the boundary of the SM bundles, orientated parallel to the axis of the bundles. Others were in spaces between the bundles and often made contact with each other. Kit-positive cells were either elongated, with several lateral branches, or stellate with branches coming from a central soma. Similar cells could be labelled with vimentin antibodies. Their relationship with intramural nerves was examined by double immunostaining with an anti-neurofilament antibody. There were frequent points of contact between Kit-positive cells and nerves, with similar findings in specimens double-immunostained with anti-neuronal nitric oxide synthase (nNOS). CONCLUSION Kit-positive ICs were found within the SM layers of the rabbit urethra, in association with nerves, on the edge of SM bundles and in the interbundle spaces. The contact with nNOS-containing neurones might imply participation in the nitrergic inhibitory neurotransmission of the urethra.
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Affiliation(s)
- Alan D Lyons
- Department of Physiology, The Queen's University of Belfast, Medical Biology Centre, Belfast, N. Ireland, UK
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Spencer NJ, Bayguinov P, Hennig GW, Park KJ, Lee HT, Sanders KM, Smith TK. Activation of neural circuitry and Ca2+ waves in longitudinal and circular muscle during CMMCs and the consequences of rectal aganglionosis in mice. Am J Physiol Gastrointest Liver Physiol 2007; 292:G546-55. [PMID: 17023548 DOI: 10.1152/ajpgi.00352.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In mammals that develop rectal aganglionosis, the aganglionic segment still exhibits spontaneous phasic contractions that contribute to dysmotility and pseudoobstruction in this region. However, almost nothing is known about the mechanisms that generate these myogenic contractions or the effects of aganglionosis on the generation of Ca(2+) waves that underlie contractions of the longitudinal muscle (LM) and circular muscle (CM). In a mouse model of Hirschsprung's disease [endothelin type B receptor-deficient (Ednrb(s-l)/Ednrb(s-l)) mice], the Ca(2+) indicator fluo-4 was used to simultaneously monitor the temporal activation and spread of intercellular Ca(2+) waves in the LM and CM during spontaneous colonic motor activities. During the intervals between colonic migrating motor complexes (CMMCs) in control mice, Ca(2+) waves discharged asynchronously between the LM and CM. However, in these same mice, during CMMCs, a burst of discreet Ca(2+) waves fired simultaneously in both muscle layers, where the propagation velocity of Ca(2+) waves significantly increased, as did the rate of initiation and number of collisions between Ca(2+) waves. Hexamethonium (300 microM) or atropine (1 microM) prevented synchronized firing of Ca(2+) waves. In the aganglionic distal colon of Ednrb(s-l)/Ednrb(s-l) mice, not only were CMMCs absent, but Ca(2+) waves between the two muscle layers fired asynchronously, despite increased propagation velocity. The generation of CMMCs in control mice involves synchronized firing of enteric motor nerves to both the LM and CM, explaining the synchronized firing of discreet Ca(2+) waves between the two muscle layers. Aganglionosis results in a sporadic and sustained asynchrony in Ca(2+) wave firing between the LM and CM and an absence of CMMCs.
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Affiliation(s)
- Nick J Spencer
- Dept of Physiology and Cell Biology, Univ of Nevada School of Medicine, Reno, NV 89557, USA.
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Kim YC, Sim JH, Kang TM, Suzuki H, Kim SR, Kwon SC, Xu WX, Lee SJ, Kim KW. Sodium-activated potassium current in guinea pig gastric myocytes. J Korean Med Sci 2007; 22:57-62. [PMID: 17297252 PMCID: PMC2693569 DOI: 10.3346/jkms.2007.22.1.57] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
This study was designed to identify and characterize Na+-activated K+ current (I(K(Na))) in guinea pig gastric myocytes under whole-cell patch clamp. After whole-cell configuration was established under 110 mM intracellular Na+ concentration ([Na+]i) at holding potential of -60 mV, a large inward current was produced by external 60 mM K+([K+]degrees). This inward current was not affected by removal of external Ca2+. K+ channel blockers had little effects on the current (p>0.05). Only TEA (5 mM) inhibited steady-state current to 68+/-2.7% of the control (p<0.05). In the presence of K+ channel blocker cocktail (mixture of Ba2+, glibenclamide, 4-AP, apamin, quinidine and TEA), a large inward current was activated. However, the amplitude of the steady-state current produced under [K+]degrees (140 mM) was significantly smaller when Na+ in pipette solution was replaced with K+- and Li+ in the presence of K+ channel blocker cocktail than under 110 mM [Na+]i. In the presence of K+ channel blocker cocktail under low Cl- pipette solution, this current was still activated and seemed K+-selective, since reversal potentials (E(rev)) of various concentrations of [K+]degrees-induced current in current/voltage (I/V) relationship were nearly identical to expected values. R-56865 (10-20 microM), a blocker of I(K(Na)), completely and reversibly inhibited this current. The characteristics of the current coincide with those of I(K(Na)) of other cells. Our results indicate the presence of I(K(Na)) in guinea pig gastric myocytes.
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Affiliation(s)
- Young Chul Kim
- Department of Physiology, Chungbuk National University, College of Medicine, Cheongju, Korea.
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Lavoie B, Balemba OB, Nelson MT, Ward SM, Mawe GM. Morphological and physiological evidence for interstitial cell of Cajal-like cells in the guinea pig gallbladder. J Physiol 2007; 579:487-501. [PMID: 17204499 PMCID: PMC2075389 DOI: 10.1113/jphysiol.2006.122861] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gallbladder smooth muscle (GBSM) exhibits spontaneous rhythmic electrical activity, but the origin and propagation of this activity are not understood. We used morphological and physiological approaches to determine whether interstitial cells of Cajal (ICC) are present in the guinea pig extrahepatic biliary tree. Light microscopic studies involving Kit tyrosine kinase immunohistochemistry and laser confocal imaging of Ca(2+) transients revealed ICC-like cells in the gallbladder. One type of ICC-like cell had elongated cell bodies with one or two primary processes and was observed mainly along GBSM bundles and nerve fibres. The other type comprised multipolar cells that were located at the origin and intersection of muscle bundles. Electron microscopy revealed ICC-like cells that were rich in mitochondria, caveolae and smooth endoplasmic reticulum and formed close appositions between themselves and with GBSM cells. Rhythmic Ca(2+) flashes, which represent Ca(2+) influx during action potentials, were synchronized in any given GBSM bundle and associated ICC-like cells. Gap junction uncouplers (1-octanol, carbenoxolone, 18beta-glycyrrhetinic acid and connexin mimetic peptide) eliminated or greatly reduced Ca(2+) flashes in GBSM, but they persisted in ICC-like cells, whereas the Kit tyrosine kinase inhibitor, imanitib mesylate, eliminated or reduced action potentials and Ca(2+) flashes in both cell types, as well as associated tissue contractions. This study provides morphological and physiological evidence for the existence of ICC-like cells in the gallbladder and presents data supporting electrical coupling between ICC-like and GBSM cells. The results support a role for ICC-like cells in the generation and propagation of spontaneous rhythmicity, and hence, the excitability of gallbladder.
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Affiliation(s)
- Brigitte Lavoie
- Department of Anatomy, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Moosmang S, Kleppisch T, Wegener J, Welling A, Hofmann F. Analysis of calcium channels by conditional mutagenesis. Handb Exp Pharmacol 2007:469-90. [PMID: 17203667 DOI: 10.1007/978-3-540-35109-2_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Ca2+ influx through various ion channels is an important determinant of the cytosolic Ca2+ concentration, which plays a pivotal role in countless cellular processes. The cardiac L-type Ca2+ channel, Ca(v)1.2, represents a major pathway for Ca2+ entry and is in many cells expressed together with other high- and low-voltage-activated Ca2+ channels. This article will focus on the use of conditional transgenic mouse models to clarify the roles of Ca2+ channels in several biological systems. The phenotypes of conditional Ca2+ channel transgenic mice have provided novel, and often unexpected, insights into the in vivo function of L-type and T-type Ca2+ channels as mediators of signaling between cell membrane and intracellular processes in blood pressure regulation, smooth muscle contractility, insulin secretion, cardiac function, sleep, learning, and memory.
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Affiliation(s)
- S Moosmang
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802 München, Germany
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Lamarca V, Grasa L, Fagundes DS, Arruebo MP, Plaza MA, Murillo MD. K+ channels involved in contractility of rabbit small intestine. J Physiol Biochem 2006; 62:227-36. [PMID: 17615948 DOI: 10.1007/bf03165751] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Most excitable cells, including gastrointestinal smooth muscle cells, express several types of K+ channels. The aim of this study was to examine the types of K' channels involved in the contractility of longitudinal smooth muscle of rabbit small intestine in vitro. Spontaneous contractions and KCl-stimulated contractions were reduced by atropine, phentolamine, propranolol, suramin, tetrodotoxin and indomethacin. The amplitude and tone of spontaneous contractions were increased by apamin, charybdotoxin, iberiotoxin, E4031, tetraetylammonium (TEA) and BaCl2. The frequency of contractions was reduced in the presence of apamin and TEA and increased by charybdotoxin. It was found that 4-aminopyridine increased the tone of spontaneous contractions and reduced the amplitude and frequency of contractions. Glibenclamide did not modify the amplitude, frequency or tone of contractions. KCl-stimulated contractions were increased by E4031, were not modified by apamin, glibenclamide, NS1619 or diazoxide, and were reduced by charybdotoxin, TEA, 4-aminopyridine or BaCl2. These results suggest that both Ca2+-activated K+ channels of small and high conductance, and HERG K+ channels and inward rectifier K+ channels participate in spontaneous contractions of small intestine. On the other hand, voltage-dependent K+ channels, HERG K+ channels, inward rectifier K+ channels and high conductance Ca2+-activated K+ channels are involved in KCl-stimulated contractions.
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Affiliation(s)
- V Lamarca
- Departamento de Farmacología y Fisiologia (Fisiologia), Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
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Balemba OB, Heppner TJ, Bonev AD, Nelson MT, Mawe GM. Calcium waves in intact guinea pig gallbladder smooth muscle cells. Am J Physiol Gastrointest Liver Physiol 2006; 291:G717-27. [PMID: 16710055 DOI: 10.1152/ajpgi.00035.2006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intracellular Ca(2+) waves and spontaneous transient depolarizations were investigated in gallbladder smooth muscle (GBSM) whole mount preparations with intact mucosal layer [full thickness (FT)] by laser confocal imaging of intracellular Ca(2+) and voltage recordings with microelectrodes, respectively. Spontaneous Ca(2+) waves arose most often near the center, but sometimes from the extremities, of GBSM cells. They propagated regeneratively by Ca(2+)-induced Ca(2+) release involving inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] receptors and were not affected by TTX and atropine (ATS). Spontaneous Ca(2+) waves and spontaneous transient depolarizations were more prevalent in FT than in isolated muscularis layer preparations and occurred with similar pattern in GBSM bundles. Ca(2+) waves were abolished by the Ins(1,4,5)P(3) receptor inhibitors 2-aminoethoxydiphenyl borate and xestospongin C and by caffeine and cyclopiazonic acid. These events were reduced by voltage-dependent calcium channels (VDCCs) inhibitors diltiazem and nifedipine, by PLC inhibitor U-73122, and by thapsigargin and ryanodine. ACh, CCK, and carbachol augmented Ca(2+) waves and induced Ca(2+) flashes. The actions of these agonists were inhibited by U-73122. These results indicate that in GBSM, discharge and propagation of Ca(2+) waves depend on sarco(endo)plasmic reticulum (SR) Ca(2+) release via Ins(1,4,5)P(3) receptors, PLC activity, Ca(2+) influx via VDCCs, and SR Ca(2+) concentration. Neurohormonal enhancement of GBSM excitability involves PLC-dependent augmentation and synchronization of SR Ca(2+) release via Ins(1,4,5)P(3) receptors. Ca(2+) waves likely reflect the activity of a fundamental unit of spontaneous activity and play an important role in the excitability of GBSM.
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Affiliation(s)
- Onesmo B Balemba
- D-406, Given Bldg., Dept. of Anatomy and Neurobiology, 89 Beaumont Ave., Univ. of Vermont, Burlington, VT 05405, USA
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Shafik A, Shafik I, Shafik AA, El-Sibai O. Interstitial cells of Cajal in erectile dysfunction. ACTA ACUST UNITED AC 2006; 52:255-62. [PMID: 16728340 DOI: 10.1080/01485010500431110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The corpora cavernosa (CC) evokes electric activity. Slow waves (SWs) appear to originate from interstitial cells of Cajal (ICCs), which seem to control the activity of the smooth muscle cells (SMC). The ICCs were demonstrated to exist in the CC. We investigated the hypothesis that the ICC distribution differs with each of the various ED types. The study comprised 62 men with ED: 16 neurogenic (NGED), 15 arteriogenic (AGED), 11 venogenic (VGED) and 22 psychogenic (PGED). 15 volunteers with normal erections acted as controls. The patients underwent a complete diagnostic evaluation. A biopsy of 3 x 3 mm from the CC was subjected to C-kit immunohistochemistry examination. Specificity control of the antisera consisted of incubation of the tissue with normal rabbit serum substituted for the primary antiserum. C-kit positive stellate-appearing cells resembling those of ICC were detected in the controls. The branches were either laterally located (multipolar) or lying at each pole (bipolar). They were distinguishable from the SMC, which were C-kit negative. ICC were detected in all specimens from patients with NGED and VGED, absent in 13/15 with AGED and scanty in PGED. ICC distribution was different in the various types of ED. It is suggested that this distribution interferes with SW discharge and the control of SMC activity with a resulting ED.
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Affiliation(s)
- A Shafik
- Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo, Egypt.
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Abstract
Brainstem parasympathetic circuits that modulate digestive functions of the stomach are comprised of afferent vagal fibers, neurons of the nucleus tractus solitarius (NTS), and the efferent fibers originating in the dorsal motor nucleus of the vagus (DMV). A large body of evidence has shown that neuronal communications between the NTS and the DMV are plastic and are regulated by the presence of a variety of neurotransmitters and circulating hormones as well as the presence, or absence, of afferent input to the NTS. These data suggest that descending central nervous system inputs as well as hormonal and afferent feedback resulting from the digestive process can powerfully regulate vago-vagal reflex sensitivity. This paper first reviews the essential "static" organization and function of vago-vagal gastric control neurocircuitry. We then present data on the opioidergic modulation of NTS connections with the DMV as an example of the "gating" of these reflexes, i.e., how neurotransmitters, hormones, and vagal afferent traffic can make an otherwise static autonomic reflex highly plastic.
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