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Farina A, Fasano A, Rosso F. Modeling of Vasomotion in Arterioles. J Theor Biol 2022; 544:111124. [DOI: 10.1016/j.jtbi.2022.111124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/03/2022] [Accepted: 04/10/2022] [Indexed: 10/18/2022]
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Abstract
Blood rheology is a challenging subject owing to the fact that blood is a mixture of a fluid (plasma) and of cells, among which red blood cells make about 50% of the total volume. It is precisely this circumstance that originates the peculiar behavior of blood flow in small vessels (i.e., roughly speaking, vessel with a diameter less than half a millimeter). In this class we find arterioles, venules, and capillaries. The phenomena taking place in microcirculation are very important in supporting life. Everybody knows the importance of blood filtration in kidneys, but other phenomena, of not less importance, are known only to a small class of physicians. Overviewing such subjects reveals the fascinating complexity of microcirculation.
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Cellular and Ionic Mechanisms of Arterial Vasomotion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:297-312. [DOI: 10.1007/978-981-13-5895-1_12] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Noordmans H, van Blooijs D, Siero J, Zwanenburg J, Klaessens J, Ramsey NF. Detailed view on slow sinusoidal, hemodynamic oscillations on the human brain cortex by Fourier transforming oxy/deoxy hyperspectral images. Hum Brain Mapp 2018; 39:3558-3573. [PMID: 29693304 PMCID: PMC6099526 DOI: 10.1002/hbm.24194] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/05/2018] [Accepted: 04/13/2018] [Indexed: 11/13/2022] Open
Abstract
Slow sinusoidal, hemodynamic oscillations (SSHOs) around 0.1 Hz are frequently seen in mammalian and human brains. In four patients undergoing epilepsy surgery, subtle but robust fluctuations in oxy- and deoxyhemoglobin were detected using hyperspectral imaging of the cortex. These SSHOs were stationary during the entire 4 to 10 min acquisition time. By Fourier filtering the oxy- and deoxyhemoglobin time signals with a small bandwidth, SSHOs became visible within localized regions of the brain, with distinctive frequencies and a continuous phase variation within that region. SSHOs of deoxyhemoglobin appeared to have an opposite phase and 11% smaller amplitude with respect to the oxyhemoglobin SSHOs. Although the origin of SSHOs remains unclear, we find indications that the observed SSHOs may embody a local propagating hemodynamic wave with velocities in line with capillary blood velocities, and conceivably related to vasomotion and maintenance of adequate tissue perfusion. Hyperspectral imaging of the human cortex during surgery allow in-depth characterization of SSHOs, and may give further insight in the nature and potential (clinical) use of SSHOs.
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Affiliation(s)
- H.J. Noordmans
- FB Medical Technology and Clinical Physics, University Medical Center UtrechtThe Netherlands
| | - D. van Blooijs
- Department of Neurology and NeurosurgeryBrain Center Rudolf Magnus, University Medical Center UtrechtThe Netherlands
| | - J.C.W. Siero
- Department of RadiologyUniversity Medical Center UtrechtThe Netherlands
- Spinoza Centre for NeuroimagingAmsterdamThe Netherlands
| | - J.J.M. Zwanenburg
- Department of RadiologyUniversity Medical Center UtrechtThe Netherlands
| | - J.H.G.M. Klaessens
- Department of Physics and Medical TechnologyVU University Medical CenterAmsterdamThe Netherlands
| | - N. F. Ramsey
- Department of Neurology and NeurosurgeryBrain Center Rudolf Magnus, University Medical Center UtrechtThe Netherlands
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Li L, Wang R, Ma KT, Li XZ, Zhang CL, Liu WD, Zhao L, Si JQ. Differential effect of calcium-activated potassium and chloride channels on rat basilar artery vasomotion. ACTA ACUST UNITED AC 2014; 34:482-490. [PMID: 25135715 DOI: 10.1007/s11596-014-1303-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/08/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Li Li
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, China
| | - Rui Wang
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
| | - Ke-Tao Ma
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, China
| | - Xin-Zhi Li
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, China
- Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Chuan-Lin Zhang
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
| | - Wei-Dong Liu
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
| | - Lei Zhao
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, China
| | - Jun-Qiang Si
- Department of Physiology, Medical College of Shihezi University, Shihezi, 832002, China.
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, China.
- Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Department of Physiology, Wuhan University School of Basic Medical Sciences, Wuhan, 430070, China.
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Lau SY, Barrett CJ, Guild SJ, Chamley LW. Necrotic trophoblast debris increases blood pressure during pregnancy. J Reprod Immunol 2013; 97:175-82. [DOI: 10.1016/j.jri.2012.12.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 11/16/2012] [Accepted: 12/13/2012] [Indexed: 11/30/2022]
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Pradhan RK, Chakravarthy VS. Informational dynamics of vasomotion in microvascular networks: a review. Acta Physiol (Oxf) 2011; 201:193-218. [PMID: 20887358 DOI: 10.1111/j.1748-1716.2010.02198.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Vasomotion refers to spontaneous oscillation of small vessels observed in many microvascular beds. It is an intrinsic phenomenon unrelated to cardiac rhythm or neural and hormonal regulation. Vasomotion is found to be particularly prominent under conditions of metabolic stress. In spite of a significant existent literature on vasomotion, its physiological and pathophysiological roles are not clear. It is thought that modulation of vasomotion by vasoactive substances released by metabolizing tissue plays a role in ensuring optimal delivery of nutrients to the tissue. Vasomotion rhythms exhibit a great variety of temporal patterns from regular oscillations to chaos. The nature of vasomotion rhythm is believed to be significant to its function, with chaotic vasomotion offering several physiological advantages over regular, periodic vasomotion. In this article, we emphasize that vasomotion is best understood as a network phenomenon. When there is a local metabolic demand in tissue, an ideal vascular response should extend beyond local microvasculature, with coordinated changes over multiple vascular segments. Mechanisms of information transfer over a vessel network have been discussed in the literature. The microvascular system may be regarded as a network of dynamic elements, interacting, either over the vascular anatomical network via gap junctions, or physiologically by exchange of vasoactive substances. Drawing analogies with spatiotemporal patterns in neuronal networks of central nervous system, we ask if properties like synchronization/desynchronization of vasomotors have special significance to microcirculation. Thus the contemporary literature throws up a novel view of microcirculation as a network that exhibits complex, spatiotemporal and informational dynamics.
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Affiliation(s)
- R K Pradhan
- Biotechnology and Bioengineering Center, Medical College of Wisconsin, Milwaukee, WI 53226-6509, USA.
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Wölfle SE, Navarro-Gonzalez MF, Grayson TH, Stricker C, Hill CE. Involvement of nonselective cation channels in the depolarisation initiating vasomotion. Clin Exp Pharmacol Physiol 2010. [DOI: 10.1111/j.1440-1681.2010.05350.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Giachini FRC, Carneiro FS, Lima VV, Carneiro ZN, Brands MW, Webb RC, Tostes RC. A key role for Na+/K+-ATPase in the endothelium-dependent oscillatory activity of mouse small mesenteric arteries. ACTA ACUST UNITED AC 2009; 42:1058-67. [PMID: 19820882 DOI: 10.1590/s0100-879x2009005000033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 09/03/2009] [Indexed: 11/21/2022]
Abstract
Oscillatory contractile activity is an inherent property of blood vessels. Various cellular mechanisms have been proposed to contribute to oscillatory activity. Mouse small mesenteric arteries display a unique low frequency contractile oscillatory activity (1 cycle every 10-12 min) upon phenylephrine stimulation. Our objective was to identify mechanisms involved in this peculiar oscillatory activity. First-order mesenteric arteries were mounted in tissue baths for isometric force measurement. The oscillatory activity was observed only in vessels with endothelium, but it was not blocked by L-NAME (100 microM) or indomethacin (10 microM), ruling out the participation of nitric oxide and prostacyclin, respectively, in this phenomenon. Oscillatory activity was not observed in vessels contracted with K+ (90 mM) or after stimulation with phenylephrine plus 10 mM K+. Ouabain (1 to 10 microM, an Na+/K+-ATPase inhibitor), but not K+ channel antagonists [tetraethylammonium (100 microM, a nonselective K+ channel blocker), Tram-34 (10 microM, blocker of intermediate conductance K+ channels) or UCL-1684 (0.1 microM, a small conductance K+ channel blocker)], inhibited the oscillatory activity. The contractile activity was also abolished when experiments were performed at 20 degrees C or in K+-free medium. Taken together, these results demonstrate that Na+/K+-ATPase is a potential source of these oscillations. The presence of alpha-1 and alpha-2 Na+/K+-ATPase isoforms was confirmed in murine mesenteric arteries by Western blot. Chronic infusion of mice with ouabain did not abolish oscillatory contraction, but up-regulated vascular Na+/K+-ATPase expression and increased blood pressure. Together, these observations suggest that the Na+/K+ pump plays a major role in the oscillatory activity of murine small mesenteric arteries.
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Affiliation(s)
- F R C Giachini
- Department of Physiology, Medical College of Georgia, Augusta, GA, USA
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Umans JG, Lindheimer MD, Hack B, Davidson-Garcia CA. Connexin Expression is not Altered in Omental Resistance Vessels from Women with Preeclampsia. Hypertens Pregnancy 2009. [DOI: 10.3109/10641950109152648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Syyong HT, Yang HHC, Trinh G, Cheung C, Kuo KH, van Breemen C. Mechanism of asynchronous Ca(2+) waves underlying agonist-induced contraction in the rat basilar artery. Br J Pharmacol 2009; 156:587-600. [PMID: 19154440 DOI: 10.1111/j.1476-5381.2008.00063.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Uridine 5'-triphosphate (UTP) is a potent vasoconstrictor of cerebral arteries and induces Ca(2+) waves in vascular smooth muscle cells (VSMCs). This study aimed to determine the mechanisms underlying UTP-induced Ca(2+) waves in VSMCs of the rat basilar artery. EXPERIMENTAL APPROACH Isometric force and intracellular Ca(2+) ([Ca(2+)](i)) were measured in endothelium-denuded rat basilar artery using wire myography and confocal microscopy respectively. KEY RESULTS Uridine 5'-triphosphate (0.1-1000 micromol.L(-1)) concentration-dependently induced tonic contraction (pEC(50) = 4.34 +/- 0.13), associated with sustained repetitive oscillations in [Ca(2+)](i) propagating along the length of the VSMCs as asynchronized Ca(2+) waves. Inhibition of Ca(2+) reuptake in sarcoplasmic reticulum (SR) by cyclopiazonic acid abolished the Ca(2+) waves and resulted in a dramatic drop in tonic contraction. Nifedipine reduced the frequency of Ca(2+) waves by 40% and tonic contraction by 52%, and the nifedipine-insensitive component was abolished by SKF-96365, an inhibitor of receptor- and store-operated channels, and KB-R7943, an inhibitor of reverse-mode Na(+)/Ca(2+) exchange. Ongoing Ca(2+) waves and tonic contraction were also abolished after blockade of inositol-1,4,5-triphosphate-sensitive receptors by 2-aminoethoxydiphenylborate, but not by high concentrations of ryanodine or tetracaine. However, depletion of ryanodine-sensitive SR Ca(2+) stores prior to UTP stimulation prevented Ca(2+) waves. CONCLUSIONS AND IMPLICATIONS Uridine 5'-triphosphate-induced Ca(2+) waves may underlie tonic contraction and appear to be produced by repetitive cycles of regenerative Ca(2+) release from the SR through inositol-1,4,5-triphosphate-sensitive receptors. Maintenance of Ca(2+) waves requires SR Ca(2+) reuptake from Ca(2+) entry across the plasma membrane via L-type Ca(2+) channels, receptor- and store-operated channels, and reverse-mode Na(+)/Ca(2+) exchange.
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Affiliation(s)
- H T Syyong
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
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Sweeney M, Wareing M, Mills TA, Baker PN, Taggart MJ. Characterisation of tone oscillations in placental and myometrial arteries from normal pregnancies and those complicated by pre-eclampsia and growth restriction. Placenta 2008; 29:356-65. [PMID: 18336903 DOI: 10.1016/j.placenta.2008.01.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 01/18/2008] [Accepted: 01/23/2008] [Indexed: 11/29/2022]
Abstract
Agonist-induced tone oscillations (rhythmic contractions and relaxations) occur in vascular beds to allow acute regulation of volume flow and thus the delivery of oxygen and nutrients to the tissue. Mechanisms responsible for the control of human placental vasomotor tone and blood flow are poorly characterized. This study aimed to characterise thromboxane-induced tone oscillations in human placental and myometrial arteries. Chorionic plate and myometrial arteries obtained from biopsies at term were mounted for isometric tension measurement. Tone oscillations were observed in chorionic arteries only when exposed to sub-maximal (<1 microM) concentrations of U46619. Slow (mean+/-SEM) frequency (2.6+/-0.5 per hour), large amplitude (39+/-7% of peak contraction) tone oscillations were elicited by 0.03 microM U46619 (n=18). In the presence of the nitric oxide synthase (NOS) inhibitor l-NNA (100 microM) the amplitude was significantly reduced (40+/-13% to 18+/-8%, P<0.05, n=6), frequency was unaltered and the bradykinin-dependent vasodilator response was reduced (68+/-13% to 40+/-19%, P<0.05, n=6). Myometrial arteries exposed to 1 microM U46619 developed tone oscillations within 10 min, which increased in amplitude over 30min occurring at relatively constant frequency. The mean amplitude of oscillations at 30 min (31+/-7%, n=16) was similar to that in chorionic arteries but the occurrence more frequent (42.8+/-9.7 per hour, P<0.001). Inhibition of NOS did not alter tone oscillations in myometrial arteries. Tone oscillations in chorionic arteries from pre-eclamptic and growth restricted (FGR) pregnancies were reduced in amplitude whereas those in myometrial arteries had increased frequency. Inhibition of NOS further reduced oscillation amplitude in chorionic arteries from FGR pregnancies. The alterations may contribute to the vasculopathology of these conditions, or, may represent compensatory mechanisms to maintain a matching of materno-placental blood flow.
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Affiliation(s)
- M Sweeney
- Institute of Cellular Medicine, School of Surgical & Reproductive Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
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Haddock RE, Hill CE. Rhythmicity in arterial smooth muscle. J Physiol 2005; 566:645-56. [PMID: 15905215 PMCID: PMC1464779 DOI: 10.1113/jphysiol.2005.086405] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 05/13/2005] [Indexed: 12/21/2022] Open
Abstract
Many arteries and arterioles exhibit rhythmical contractions which are synchronous over considerable distances. This vasomotion is likely to assist in tissue perfusion especially during periods of altered metabolism or perfusion pressure. While the mechanism underlying vascular rhythmicity has been investigated for many years, it has only been recently, with the advent of imaging techniques for visualizing intracellular calcium release, that significant advances have been made. These methods, when combined with mechanical and electrophysiological recordings, have demonstrated that the rhythm depends critically on calcium released from intracellular stores within the smooth muscle cells and on cell coupling via gap junctions to synchronize oscillations in calcium release amongst adjacent cells. While these factors are common to all vessels studied to date, the contribution of voltage-dependent channels and the endothelium varies amongst different vessels. The basic mechanism for rhythmical activity in arteries thus differs from its counterpart in non-vascular smooth muscle, where specific networks of pacemaker cells generate electrical potentials which drive activity within the otherwise quiescent muscle cells.
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Affiliation(s)
- Rebecca E Haddock
- Division of Neuroscience, John Curtin School of Medical Research, GPO Box 334, Canberra, ACT, 2601, Australia.
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Abstract
Four connexin (Cx) molecules, namely Cx37, Cx40, Cx43 and Cx45, are expressed in the gap junctions that exist within and between the cellular layers of arteries. Endothelial cells are well coupled by large gap junctions expressing Cx37, Cx40 and, to a lesser extent, Cx43, whose expression may be more subject to regulation by physical factors. Smooth muscle cells are more heterogeneously coupled by gap junctions that are small and rare. The identity of the Cx expressed in the media may vary among different arteries. Myoendothelial gap junctions are small and more common in resistance arteries with fewer layers of smooth muscle cells. Given the small size of these gap junctions and the rapid turnover rate of Cxs, homocellular coupling in the media and heterocellular coupling between the cell layers may be subject to more dynamic control than coupling in the endothelium. Vascular gap junctions have been implicated in a number of vasomotor responses that may regulate vascular tone and blood pressure. These include the mechanism of action of the vasodilator, endothelium-derived hyperpolarizing factor (EDHF), the myogenic constriction to intramural pressure increase, the spontaneous or agonist-induced vasomotion of arteries and arterioles and the spreading vasodilation and constriction observed in microcirculatory networks. Few data are available on Cx expression in the media of resistance arteries during hypertension. Changes in the expression of Cx43 described in the media of the aorta of hypertensive rats vary with the hypertensive model studied and are likely to represent adaptations to structural changes in the vascular wall. In contrast, in the endothelium of the caudal and mesenteric arteries of spontaneously hypertensive rats, expression of Cxs is significantly decreased compared with arteries from normotensive rats and this decrease is reversed by inhibitors of the renin-angiotensin system. During hypertension, the activity of EDHF is decreased in the mesenteric artery, but this occurs much later than the initial increase in blood pressure and the decrease in endothelial Cxs, suggesting that changes in EDHF may not be causally related to hypertension or to the changes in endothelial Cxs. Upregulation of the myogenic response and the incidence of vasomotion has been reported in hypertension. Little is currently known of the effects of hypertension on spreading vasomotor responses. Deletion of specific Cxs in genetically modified mice is complicated by neonatal lethality or coordinate regulation and compensatory changes in the remaining Cxs. Nevertheless, mice in which Cx40 has been deleted are hypertensive and spreading vasodilatory responses are significantly impaired. Determination of a role for specific Cxs in the control of blood pressure must await the development of animals in which Cx expression can be modulated in a more complex temporal and tissue-specific manner.
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Affiliation(s)
- Nicole M Rummery
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
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Brueggemann LI, Martin BL, Barakat J, Byron KL, Cribbs LL. Low voltage-activated calcium channels in vascular smooth muscle: T-type channels and AVP-stimulated calcium spiking. Am J Physiol Heart Circ Physiol 2004; 288:H923-35. [PMID: 15498818 DOI: 10.1152/ajpheart.01126.2003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An important path of extracellular calcium influx in vascular smooth muscle (VSM) cells is through voltage-activated Ca2+ channels of the plasma membrane. Both high (HVA)- and low (LVA)-voltage-activated Ca2+ currents are present in VSM cells, yet little is known about the relevance of the LVA T-type channels. In this report, we provide molecular evidence for T-type Ca2+ channels in rat arterial VSM and characterize endogenous LVA Ca2+ currents in the aortic smooth muscle-derived cell line A7r5. AVP is a vasoconstrictor hormone that, at physiological concentrations, stimulates Ca2+ oscillations (spiking) in monolayer cultures of A7r5 cells. The present study investigated the role of T-type Ca2+ channels in this response with a combination of pharmacological and molecular approaches. We demonstrate that AVP-stimulated Ca2+ spiking can be abolished by mibefradil at low concentrations (<1 microM) that should not inhibit L-type currents. Infection of A7r5 cells with an adenovirus containing the Cav3.2 T-type channel resulted in robust LVA Ca2+ currents but did not alter the AVP-stimulated Ca2+ spiking response. Together these data suggest that T-type Ca2+ channels are necessary for the onset of AVP-stimulated calcium oscillations; however, LVA Ca2+ entry through these channels is not limiting for repetitive Ca2+ spiking observed in A7r5 cells.
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Affiliation(s)
- Lioubov I Brueggemann
- Department of Medicine, Cardiovascular Institute, Loyola University Medical Center, Maywood, Illinois 60153, USA
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Haddock RE, Hill CE. Differential activation of ion channels by inositol 1,4,5-trisphosphate (IP3)- and ryanodine-sensitive calcium stores in rat basilar artery vasomotion. J Physiol 2002; 545:615-27. [PMID: 12456838 PMCID: PMC2290697 DOI: 10.1113/jphysiol.2002.027904] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Spontaneous, rhythmical contractions, or vasomotion, can be recorded from cerebral vessels under both normal physiological and pathophysiological conditions. Using electrophysiology to study changes in membrane potential, the ratiometric calcium indicator Fura-2 AM to study changes in [Ca(2+)](i) in both the arterial wall and in individual smooth muscle cells (SMCs), and video microscopy to study changes in vessel diameter, we have investigated the cellular mechanisms underlying vasomotion in the juvenile rat basilar artery. During vasomotion, rhythmical oscillations in both membrane potential and [Ca(2+)](i) were found to precede rhythmical contractions. Nifedipine depolarized SMCs and abolished rhythmical contractions and depolarizations. [Ca(2+)](i) oscillations in the arterial wall became reduced and irregular, while [Ca(2+)](i) oscillations in adjacent SMCs were no longer synchronized. BAPTA-AM, thapsigargin and U73122 hyperpolarized SMCs, relaxed the vessel, decreased basal calcium levels and abolished vasomotion. Chloride substitution abolished rhythmical activity, depolarized SMCs, increased basal calcium levels and constricted the vessel, while niflumic acid and DIDS abolished vasomotion. Ryanodine, charybdotoxin and TRAM-34, but not iberiotoxin, 4-aminopyridine or apamin, each depolarized SMCs and increased the frequency of rhythmical depolarizations and [Ca(2+)](i) oscillations. We conclude that vasomotion in the basilar artery depends on the release of intracellular calcium from IP(3) (inositol 1,4,5,-trisphosphate)-sensitive stores which activates calcium-dependent chloride channels to depolarize SMCs. Depolarization in turn activates voltage-dependent calcium channels, synchronizing contractions of adjacent cells through influx of extracellular calcium. Subsequent calcium-induced calcium release from ryanodine-sensitive stores activates an intermediate conductance potassium channel, hyperpolarizing the SMCs and providing a negative feedback pathway for regeneration of the contractile cycle.
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Affiliation(s)
- R E Haddock
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, GPO Box 334, Canberra, ACT 2601, Australia.
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Haddock RE, Hirst GDS, Hill CE. Voltage independence of vasomotion in isolated irideal arterioles of the rat. J Physiol 2002; 540:219-29. [PMID: 11927681 PMCID: PMC2290219 DOI: 10.1113/jphysiol.2001.013698] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The cellular mechanisms underlying vasomotion of irideal arterioles from juvenile rats have been studied using electrophysiological methods, ratiometric calcium measurements and video microscopy. Vasomotion was not affected by removal of the endothelium. Spontaneous contractions were preceded by spontaneous depolarizations. Both were abolished by the intracellular calcium chelator, BAPTA AM (20 microM), but not by ryanodine (10 microM), suggesting a dependence on the cyclical release of calcium from intracellular stores, other than those operated by ryanodine receptors. Oscillations were little changed when the membrane potential of short segments of arteriole was either depolarized or hyperpolarized. When the segments were voltage clamped, oscillating inward currents were recorded, indicating that the changes in membrane potential were voltage independent. Vasomotion was preceded by intracellular calcium oscillations and both were abolished by inhibitors of phospholipase C (U73122, 10 microM), phospholipase A(2) (AACOCF(3), 30 microM) and protein kinase C (chelerythrine chloride, 5 microM, and myristoylated protein kinase C peptide, 10 microM). Inhibition of vasomotion by the dual lipoxygenase and cyclo-oxygenase inhibitor, NDGA (10 microM), the lipoxygenase inhibitor, ETI (1 microM) but not by the cyclo-oxygenase inhibitors, aspirin (10 microM) and indomethacin (10 microM), or the cytochrome P450 inhibitor 17-ODYA (10 microM), suggested an involvement of the lipoxygenase pathway. The observations suggest that vasomotion of iris arterioles is voltage independent and results from the cyclical release of calcium from IP(3)-sensitive stores which are activated by cross talk between the phospholipase C and phospholipase A(2) pathways in vascular smooth muscle.
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Affiliation(s)
- R E Haddock
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, GPO Box 334, Canberra, ACT, 2601, Australia.
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Byron KL, Lucchesi PA. Signal transduction of physiological concentrations of vasopressin in A7r5 vascular smooth muscle cells. A role for PYK2 and tyrosine phosphorylation of K+ channels in the stimulation of Ca2+ spiking. J Biol Chem 2002; 277:7298-307. [PMID: 11739373 DOI: 10.1074/jbc.m104726200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The signal transduction pathway linking physiological concentrations of [Arg(8)]vasopressin (AVP) to an increase in frequency of Ca(2+) spiking was examined in confluent cultures of A7r5 vascular smooth muscle cells. Immunoprecipitation/Western blot studies revealed a robust increase in tyrosine phosphorylation of the non-receptor tyrosine kinase, PYK2, in A7r5 cells treated with 4beta-phorbol 12-myristate 13-acetate or ionomycin. 100 pm AVP also induced PYK2 tyrosine phosphorylation, and this effect was inhibited by protein kinase C inhibitors Ro-31-8220 (1-10 microm) or chelerythrine chloride (1-20 microm). In fura-2-loaded A7r5 cells, the stimulation of Ca(2+) spiking by 100 pm AVP or 1 nm 4beta-phorbol 12-myristate 13-acetate was completely blocked by PP2 (10 microm, a Src family kinase inhibitor). Salicylate (20 mm, recently identified as a PYK2 inhibitor) and the tyrosine kinase inhibitor, tyrphostin A47 (50 microm), but not its inactive analog, tyrphostin A63, also blocked AVP-stimulated Ca(2+) spiking. PYK2 phosphorylation was inhibited by both PP2 and salicylate, whereas tyrphostin A47 failed to inhibit PYK2 tyrosine phosphorylation. ERK1/2 kinases did not appear to be involved because 1) 100 pm AVP did not appreciably increase ERK1/2 phosphorylation and U-0126 (2.5 microm) did not inhibit AVP-stimulated Ca(2+) spiking; and 2) epidermal growth factor (10 nm) robustly stimulated ERK1/2 phosphorylation but did not induce Ca(2+) spiking. Delayed rectifier K(+) channels may mediate the PYK2 activity because Kv1.2 channel protein co-immunoprecipitated with PYK2 and tyrosine phosphorylation of Kv1.2 was stimulated by AVP and inhibited by Ro-31-8220, PP2, and salicylate but not tyrphostin A47. Our findings are consistent with a role for PYK2 and phosphorylation of K(+) channels in the stimulation of Ca(2+) spiking by physiological concentrations of AVP.
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Affiliation(s)
- Kenneth L Byron
- Department of Medicine, Cardiovascular Institute, Loyola University Chicago, 2160 South First Avenue, Maywood, IL 60153, USA.
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Meyer C, de Vries G, Davidge ST, Mayes DC. Reassessing the mathematical modeling of the contribution of vasomotion to vascular resistance. J Appl Physiol (1985) 2002; 92:888-9. [PMID: 11838438 DOI: 10.1152/jappl.2002.92.2.888] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Gratton RJ, Gandley RE, Genbacev O, McCarthy JF, Fisher SJ, McLaughlin MK. Conditioned medium from hypoxic cytotrophoblasts alters arterial function. Am J Obstet Gynecol 2001; 184:984-90. [PMID: 11303209 DOI: 10.1067/mob.2001.110499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Our goal was to test the hypothesis that cytotrophoblasts, under low oxygen tension, release substances that affect vascular behavior. STUDY DESIGN We studied the vascular response to the vasoconstrictors phenylephrine (receptor dependent) and potassium (receptor independent), the relaxation response to methacholine, and the vasomotor behavior of isolated resistance (mesenteric) arteries from early pregnant rats after incubation in conditioned medium from first-trimester cytotrophoblasts, maintained in standard or hypoxic (2%; 14 mm Hg) culture conditions. RESULTS After incubation in medium from hypoxic cytotrophoblasts, arterial segments were more responsive to phenylephrine and to potassium-induced constriction but were less responsive to methacholine, and the vasomotor activity was increased compared with that found in vessels incubated in control medium. CONCLUSIONS These changes in vascular behavior are similar to those reported in isolated arteries from women with preeclampsia. These studies provide evidence which suggests that the link between abnormal placentation and maternal vascular abnormality in preeclampsia is the elaboration of vasoactive factors by cytotrophoblasts in response to hypoxia.
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Affiliation(s)
- R J Gratton
- Department of Obstetrics, Gynecology, and Reproductive Science, University of Pittsburgh School of Medicine, Pennsylvania, USA
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Abstract
The control and maintenance of vascular tone is due to a balance between vasoconstrictor and vasodilator pathways. Vasomotor responses to neural, metabolic and physical factors vary between vessels in different vascular beds, as well as along the same bed, particularly as vessels become smaller. These differences result from variation in the composition of neurotransmitters released by perivascular nerves, variation in the array and activation of receptor subtypes expressed in different vascular beds and variation in the signal transduction pathways activated in either the vascular smooth muscle or endothelial cells. As the study of vasomotor responses often requires pre-existing tone, some of the reported heterogeneity in the relative contributions of different vasodilator mechanisms may be compounded by different experimental conditions. Biochemical variations, such as the expression of ion channels, connexin subtypes and other important components of second messenger cascades, have been documented in the smooth muscle and endothelial cells in different parts of the body. Anatomical variations, in the presence and prevalence of gap junctions between smooth muscle cells, between endothelial cells and at myoendothelial gap junctions, between the two cell layers, have also been described. These factors will contribute further to the heterogeneity in local and conducted responses.
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Affiliation(s)
- C E Hill
- Autonomic Synapse Group, Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra 0200 ACT, Australia.
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Fan J, Byron KL. Ca2+ signalling in rat vascular smooth muscle cells: a role for protein kinase C at physiological vasoconstrictor concentrations of vasopressin. J Physiol 2000; 524 Pt 3:821-31. [PMID: 10790161 PMCID: PMC2269909 DOI: 10.1111/j.1469-7793.2000.00821.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/1999] [Accepted: 02/16/2000] [Indexed: 01/12/2023] Open
Abstract
Physiological vasoconstrictor concentrations of Arg8-vasopressin (AVP, 10-100 pM) stimulate oscillations (spikes) in cytosolic free Ca2+ concentration ([Ca2+]i) in A7r5 rat vascular smooth muscle cells. These Ca2+ spikes are dependent on L-type voltage-sensitive Ca2+ channels and increase in frequency with increasing AVP concentration. The signal transduction pathway responsible for this effect was examined in fura-2-loaded A7r5 cell monolayers. The serine/threonine phosphatase inhibitor calyculin A (5 nM) sensitized A7r5 cells to AVP, resulting in the stimulation of Ca2+ spiking by 1-10 pM AVP. Calyculin A alone did not stimulate Ca2+ spiking. The protein kinase C (PKC) activator 4beta-phorbol 12-myristate 13-acetate (PMA, 100 pM to 200 nM), also stimulated Ca2+ spiking and this effect was additive with a submaximal concentration of AVP (50 pM). The PKC inhibitors Ro-31-8220 (1 microM) and calphostin C (250 nM) completely blocked the stimulation of Ca2+ spiking by either PMA or AVP. alpha, beta, gamma, delta, epsilon, zeta and &lamdda; isoforms of PKC were detected in A7r5 cells by Western blot analysis. Time-dependent redistribution of PKC-alpha, -delta and -epsilon isoforms between the membrane and cytosolic fractions occurred in response to 100 pM AVP. Pretreatment for 24 h with 1 microM PMA downregulated expression of PKC-alpha and -delta, but not PKC-epsilon, and prevented the Ca2+-spiking responses to either 1 nM PMA or 100 pM AVP. Neither the release of intracellular Ca2+ by 1 microM AVP nor the increase in [Ca2+]i in response to elevated extracellular [K+] was prevented by the PMA pretreatment. We conclude that PKC activation is a necessary step in the signal transduction pathway linking low concentrations of AVP to Ca2+ spiking in A7r5 cells.
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Affiliation(s)
- J Fan
- Department of Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
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Hill CE, Eade J, Sandow SL. Mechanisms underlying spontaneous rhythmical contractions in irideal arterioles of the rat. J Physiol 1999; 521 Pt 2:507-16. [PMID: 10581319 PMCID: PMC2269675 DOI: 10.1111/j.1469-7793.1999.00507.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
1. Mechanisms underlying spontaneous rhythmical contractions have been studied in irideal arterioles of the rat using video microscopy and electrophysiology. 2. Rhythmical contractions (4 min-1) were more common during the second and third postnatal weeks and were always preceded by large, slow depolarizations (5-40 mV). 3. Spontaneous contractions were unaffected by tetrodotoxin (1 microM), neurotransmitter receptor antagonists, the sympathetic neurone blocker, guanethidine (5 microM) or sensory neurotoxin, capsaicin (1 microM). 4. Stimulation of sensory nerves inhibited spontaneous activity and this was not prevented by L-NAME (10 microm). 5. L-NAME (10 microm) caused an increase in frequency of spontaneous contractions, while forskolin (30 nM), in the presence of L-NAME, abolished spontaneous, but not nerve-mediated, contractions. 6. Spontaneous activity was not affected by felodipine (1 nM) or nifedipine (1 microM), but was abolished by cadmium chloride (1 microM) or superfusion with calcium-free solution. 7. Caffeine (1 mM), thapsigargin (2 microM) and cyclopiazonic acid (3 microM), but not ryanodine (3 microM), abolished spontaneous and nerve-mediated contractions. After preincubation in L-NAME (10 microM), cyclopiazonic acid abolished spontaneous contractions only. 8. Spontaneous depolarizations and contractions were abolished by 18alpha-glycyrrhetinic acid (20 microM). 9. Results suggest that spontaneous rhythmical contractions are myogenic and result from the cyclical release of calcium from intracellular stores, without a contribution from voltage-dependent calcium channels. Intercellular coupling through gap junctions appears to be essential for co-ordination of these events which could be modulated by nitric oxide and increases in cAMP. The possibility that different intracellular stores underly spontaneous and nerve-mediated contractions is discussed.
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Affiliation(s)
- C E Hill
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, GPO Box 334, Canberra, ACT 2601, Australia.
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Affiliation(s)
- J M Roberts
- Magee-Womens Research Institute, 204 Craft Avenue, Pittsburgh, PA 16213, USA.
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Umans JG. Author's reply:. Am J Kidney Dis 1999. [DOI: 10.1016/s0272-6386(99)70440-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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