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Hassan N, Murray BG, Jagadeeshan S, Thomas R, Katselis GS, Ianowski JP. Intracellular Ca 2+ oscillation frequency and amplitude modulation mediate epithelial apical and basolateral membranes crosstalk. iScience 2024; 27:108629. [PMID: 38188522 PMCID: PMC10767210 DOI: 10.1016/j.isci.2023.108629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/04/2023] [Accepted: 11/30/2023] [Indexed: 01/09/2024] Open
Abstract
Since the early seminal studies on epithelial solute transport, it has been understood that there must be crosstalk among different members of the transport machinery to coordinate their activity and, thus, generate localized electrochemical gradients that force solute flow in the required direction that would otherwise be thermodynamically unfavorable. However, mechanisms underlying intracellular crosstalk remain unclear. We present evidence that crosstalk between apical and basolateral membrane transporters is mediated by intracellular Ca2+ signaling in insect renal epithelia. Ion flux across the basolateral membrane is encoded in the intracellular Ca2+ oscillation frequency and amplitude modulation and that information is used by the apical membrane to adjust ion flux accordingly. Moreover, imposing experimentally generated intracellular Ca2+ oscillation modulation causes cells to predictably adjust their ion transport properties. Our results suggest that intracellular Ca2+ oscillation frequency and amplitude modulation encode information on transmembrane ion flux that is required for crosstalk.
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Affiliation(s)
- Noman Hassan
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
| | - Brendan G. Murray
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
| | | | - Robert Thomas
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
| | - George S. Katselis
- Department of Medicine, Division of Canadian Centre for Rural and Agricultural Health, College of Medicine, University of Saskatchewan, Saskatoon S7N 2Z4, Canada
| | - Juan P. Ianowski
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
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2
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Beyenbach KW. Voltages and resistances of the anterior Malpighian tubule of Drosophila melanogaster. ACTA ACUST UNITED AC 2019; 222:jeb.201574. [PMID: 31043456 DOI: 10.1242/jeb.201574] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Accepted: 04/25/2019] [Indexed: 01/12/2023]
Abstract
The small size of Malpighian tubules in the fruit fly Drosophila melanogaster has discouraged measurements of the transepithelial electrical resistance. The present study introduces two methods for measuring the transepithelial resistance in isolated D . melanogaster Malpighian tubules using conventional microelectrodes and PClamp hardware and software. The first method uses three microelectrodes to measure the specific transepithelial resistance normalized to tubule length or luminal surface area for comparison with resistances of other epithelia. The second method uses only two microelectrodes to measure the relative resistance for comparing before and after effects in a single Malpighian tubule. Knowledge of the specific transepithelial resistance allows the first electrical model of electrolyte secretion by the main segment of the anterior Malpighian tubule of D . melanogaster The electrical model is remarkably similar to that of the distal Malpighian tubule of Aedes aegypti when tubules of Drosophila and Aedes are studied in vitro under the same experimental conditions. Thus, despite 189 millions of years of evolution separating these two genera, the electrophysiological properties of their Malpighian tubules remains remarkably conserved.
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Affiliation(s)
- Klaus W Beyenbach
- Department of Biology/Chemistry, Division of Animal Physiology, University of Osnabrück, Barbarastrasse 11, Osnabrück 49076, Germany
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3
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Feingold D, Knogler L, Starc T, Drapeau P, O'Donnell MJ, Nilson LA, Dent JA. secCl is a cys-loop ion channel necessary for the chloride conductance that mediates hormone-induced fluid secretion in Drosophila. Sci Rep 2019; 9:7464. [PMID: 31097722 PMCID: PMC6522505 DOI: 10.1038/s41598-019-42849-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 04/10/2019] [Indexed: 01/09/2023] Open
Abstract
Organisms use circulating diuretic hormones to control water balance (osmolarity), thereby avoiding dehydration and managing excretion of waste products. The hormones act through G-protein-coupled receptors to activate second messenger systems that in turn control the permeability of secretory epithelia to ions like chloride. In insects, the chloride channel mediating the effects of diuretic hormones was unknown. Surprisingly, we find a pentameric, cys-loop chloride channel, a type of channel normally associated with neurotransmission, mediating hormone-induced transepithelial chloride conductance. This discovery is important because: 1) it describes an unexpected role for pentameric receptors in the membrane permeability of secretory epithelial cells, and 2) it suggests that neurotransmitter-gated ion channels may have evolved from channels involved in secretion.
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Affiliation(s)
- Daniel Feingold
- Department of Biology, McGill University, 1205 Dr. Penfield, Montréal, Québec, H3A 1B1, Canada
| | - Laura Knogler
- Department of Neurosciences, Research Centre of the University of Montréal Hospital Centre, Montréal, Québec, Canada
- Max Planck Institute of Neurobiology, Sensorimotor Control Research Group, Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Tanja Starc
- Institute of Neuroscience, Technische Universität München, Biedersteiner Str. 29, München, Bau 601D-80802, Germany
| | - Pierre Drapeau
- Department of Neurosciences, Research Centre of the University of Montréal Hospital Centre, Montréal, Québec, Canada
| | - Michael J O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada
| | - Laura A Nilson
- Department of Biology, McGill University, 1205 Dr. Penfield, Montréal, Québec, H3A 1B1, Canada
| | - Joseph A Dent
- Department of Biology, McGill University, 1205 Dr. Penfield, Montréal, Québec, H3A 1B1, Canada.
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Agrawal P, Houl JH, Gunawardhana KL, Liu T, Zhou J, Zoran MJ, Hardin PE. Drosophila CRY Entrains Clocks in Body Tissues to Light and Maintains Passive Membrane Properties in a Non-clock Body Tissue Independent of Light. Curr Biol 2017; 27:2431-2441.e3. [PMID: 28781048 DOI: 10.1016/j.cub.2017.06.064] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 05/24/2017] [Accepted: 06/26/2017] [Indexed: 12/20/2022]
Abstract
Circadian (∼24 hr) clocks regulate daily rhythms in physiology, metabolism, and behavior via cell-autonomous transcriptional feedback loops. In Drosophila, the blue-light photoreceptor CRYPTOCHROME (CRY) synchronizes these feedback loops to light:dark cycles by binding to and degrading TIMELESS (TIM) protein. CRY also acts independently of TIM in Drosophila to alter potassium channel conductance in arousal neurons after light exposure, and in many animals CRY acts independently of light to repress rhythmic transcription. CRY expression has been characterized in the Drosophila brain and eyes, but not in peripheral clock and non-clock tissues in the body. To investigate CRY expression and function in body tissues, we generated a GFP-tagged-cry transgene that rescues light-induced behavioral phase resetting in cry03 mutant flies and sensitively reports GFP-CRY expression. In bodies, CRY is detected in clock-containing tissues including Malpighian tubules, where it mediates both light-dependent TIM degradation and clock function. In larval salivary glands, which lack clock function but are amenable to electrophysiological recording, CRY prevents membrane input resistance from falling to low levels in a light-independent manner. The ability of CRY to maintain high input resistance in these non-excitable cells also requires the K+ channel subunits Hyperkinetic, Shaker, and ether-a-go-go. These findings for the first time define CRY expression in Drosophila peripheral tissues and reveal that CRY acts together with K+ channels to maintain passive membrane properties in a non-clock-containing peripheral tissue independent of light.
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Affiliation(s)
- Parul Agrawal
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
| | - Jerry H Houl
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
| | - Kushan L Gunawardhana
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
| | - Tianxin Liu
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
| | - Jian Zhou
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
| | - Mark J Zoran
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
| | - Paul E Hardin
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA.
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5
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Piermarini PM, Dunemann SM, Rouhier MF, Calkins TL, Raphemot R, Denton JS, Hine RM, Beyenbach KW. Localization and role of inward rectifier K(+) channels in Malpighian tubules of the yellow fever mosquito Aedes aegypti. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 67:59-73. [PMID: 26079629 DOI: 10.1016/j.ibmb.2015.06.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 06/03/2015] [Accepted: 06/07/2015] [Indexed: 05/04/2023]
Abstract
Malpighian tubules of adult female yellow fever mosquitoes Aedes aegypti express three inward rectifier K(+) (Kir) channel subunits: AeKir1, AeKir2B and AeKir3. Here we 1) elucidate the cellular and membrane localization of these three channels in the Malpighian tubules, and 2) characterize the effects of small molecule inhibitors of AeKir1 and AeKir2B channels (VU compounds) on the transepithelial secretion of fluid and electrolytes and the electrophysiology of isolated Malpighian tubules. Using subunit-specific antibodies, we found that AeKir1 and AeKir2B localize exclusively to the basolateral membranes of stellate cells and principal cells, respectively; AeKir3 localizes within intracellular compartments of both principal and stellate cells. In isolated tubules bathed in a Ringer solution containing 34 mM K(+), the peritubular application of VU590 (10 μM), a selective inhibitor of AeKir1, inhibited transepithelial fluid secretion 120 min later. The inhibition brings rates of transepithelial KCl and fluid secretion to 54% of the control without a change in transepithelial NaCl secretion. VU590 had no effect on the basolateral membrane voltage (Vbl) of principal cells, but it significantly reduced the cell input conductance (gin) to values 63% of the control within ∼90 min. In contrast, the peritubular application of VU625 (10 μM), an inhibitor of both AeKir1 and AeKir2B, started to inhibit transepithelial fluid secretion as early as 60 min later. At 120 min after treatment, VU625 was more efficacious than VU590, inhibiting transepithelial KCl and fluid secretion to ∼35% of the control without a change in transepithelial NaCl secretion. Moreover, VU625 caused the Vbl and gin of principal cells to respectively drop to values 62% and 56% of the control values within only ∼30 min. Comparing the effects of VU590 with those of VU625 allowed us to estimate that AeKir1 and AeKir2B respectively contribute to 46% and 20% of the transepithelial K(+) secretion when the tubules are bathed in a Ringer solution containing 34 mM K(+). Thus, we uncover an important role of AeKir1 and stellate cells in transepithelial K(+) transport under conditions of peritubular K(+) challenge. The physiological role of AeKir3 in intracellular membranes of both stellate and principal cells remains to be determined.
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Affiliation(s)
- Peter M Piermarini
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA.
| | - Sonja M Dunemann
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Matthew F Rouhier
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Travis L Calkins
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Rene Raphemot
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Rebecca M Hine
- Department of Biomedical Sciences, VRT 8004, Cornell University, Ithaca, NY 14853, USA
| | - Klaus W Beyenbach
- Department of Biomedical Sciences, VRT 8004, Cornell University, Ithaca, NY 14853, USA
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Chloride channels in stellate cells are essential for uniquely high secretion rates in neuropeptide-stimulated Drosophila diuresis. Proc Natl Acad Sci U S A 2014; 111:14301-6. [PMID: 25228763 DOI: 10.1073/pnas.1412706111] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Epithelia frequently segregate transport processes to specific cell types, presumably for improved efficiency and control. The molecular players underlying this functional specialization are of particular interest. In Drosophila, the renal (Malpighian) tubule displays the highest per-cell transport rates known and has two main secretory cell types, principal and stellate. Electrogenic cation transport is known to reside in the principal cells, whereas stellate cells control the anion conductance, but by an as-yet-undefined route. Here, we resolve this issue by showing that a plasma membrane chloride channel, encoded by ClC-a, is exclusively expressed in the stellate cell and is required for Drosophila kinin-mediated induction of diuresis and chloride shunt conductance, evidenced by chloride ion movement through the stellate cells, leading to depolarization of the transepithelial potential. By contrast, ClC-a knockdown had no impact on resting secretion levels. Knockdown of a second CLC gene showing highly abundant expression in adult Malpighian tubules, ClC-c, did not impact depolarization of transepithelial potential after kinin stimulation. Therefore, the diuretic action of kinin in Drosophila can be explained by an increase in ClC-a-mediated chloride conductance, over and above a resting fluid transport level that relies on other (ClC-a-independent) mechanisms or routes. This key segregation of cation and anion transport could explain the extraordinary fluid transport rates displayed by some epithelia.
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7
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Ruka KA, Miller AP, Blumenthal EM. Inhibition of diuretic stimulation of an insect secretory epithelium by a cGMP-dependent protein kinase. Am J Physiol Renal Physiol 2013; 304:F1210-6. [PMID: 23445619 DOI: 10.1152/ajprenal.00231.2012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The rate of urine secretion by insect Malpighian tubules (MTs) is regulated by multiple diuretic and antidiuretic hormones, often working either synergistically or antagonistically. In the Drosophila melanogaster MT, only diuretic factors have been reported. Two such agents are the biogenic amine tyramine (TA) and the peptide drosokinin (DK), both of which act on the stellate cells of the tubule to increase transepithelial chloride conductance. In the current study, TA and DK signaling was quantified by microelectrode recording of the transepithelial potential in isolated Drosophila MTs. Treatment of tubules with cGMP caused a significant reduction in the depolarizing responses to both TA and DK, while cAMP had no effect on these responses. To determine whether a specific cGMP-dependent protein kinase (PKG) was mediating this inhibition, PKG expression was knocked down by RNAi in either the principal cells or the stellate cells. Knockdown of Pkg21D in the stellate cells eliminated the modulation of TA and DK signaling. Knockdown of Pkg21D with a second RNAi construct also reduced the modulation of TA signaling. In contrast, knockdown of the expression of foraging or CG4839, which encodes a known and a putative PKG, respectively, had no effect. These data indicate that cGMP, acting through the Pkg21D gene product in the stellate cells, can inhibit signaling by the diuretic agents TA and DK. This represents a novel function for cGMP and PKG in the Drosophila MT and suggests the existence of an antidiuretic hormone in Drosophila.
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Affiliation(s)
- Kristen A Ruka
- Dept. of Biological Sciences, Marquette Univ., P.O. Box 1881, Milwaukee, WI 53201-1881, USA
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8
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Miyauchi JT, Piermarini PM, Yang JD, Gilligan DM, Beyenbach KW. Roles of PKC and phospho-adducin in transepithelial fluid secretion by Malpighian tubules of the yellow fever mosquito. Tissue Barriers 2013; 1. [PMID: 24062972 PMCID: PMC3779481 DOI: 10.4161/tisb.23120] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The diuretic hormone aedeskinin-III is known to increase the paracellular Cl- conductance in Malpighian (renal) tubules of the mosquito Aedes aegypti via a G protein-coupled receptor. The increase serves the blood-meal-initiated diuresis and is associated with elevated levels of Ca2+ and phosphorylated adducin in the cytosol of tubule. In the present study we have cloned adducin in Aedes Malpighian tubules and investigated its physiological roles. Immunolabeling experiments are consistent with the association of adducin with the cortical cytoskeleton, especially near the apical brush border of the tubule. An antibody against phosphorylated adducin revealed the transient phosphorylation of adducin 2 min after stimulating tubules with aedeskinin-III. The PKC inhibitor bisindolylmaleimide-I blocked the phosphorylation of adducin as well as the electrophysiological and diuretic effects of aedeskinin-III. Bisindolylmaleimide-I also inhibited fluid secretion in control tubules. Phorbol 12-myristate 13-acetate increased phosphorylated adducin levels in Malpighian tubules, but it inhibited fluid secretion. Thus, the phosphorylation of adducin by PKC alone is insufficient to trigger diuretic rates of fluid secretion; elevated levels of intracellular Ca2+ may also be required. The above results suggest that the phosphorylation of adducin, which is known to destabilize the cytoskeleton, may (1) facilitate the traffic of transporters into the apical brush border supporting diuretic rates of cation secretion and (2) destabilize proteins in the septate junction thereby enabling paracellular anion (Cl-) secretion at diuretic rates. Moreover, PKC and the phosphorylation of adducin play a central role in control and diuretic tubules, consistent with the dynamic behavior of both transcellular and paracellular transport pathways.
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Affiliation(s)
- Jeremy T Miyauchi
- Department of Biomedical Sciences; College of Veterinary Medicine; Cornell University; Ithaca, NY USA
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Schepel SA, Fox AJ, Miyauchi JT, Sou T, Yang JD, Lau K, Blum AW, Nicholson LK, Tiburcy F, Nachman RJ, Piermarini PM, Beyenbach KW. The single kinin receptor signals to separate and independent physiological pathways in Malpighian tubules of the yellow fever mosquito. Am J Physiol Regul Integr Comp Physiol 2010; 299:R612-22. [PMID: 20538895 DOI: 10.1152/ajpregu.00068.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the past, we have used the kinins of the cockroach Leucophaea (the leucokinins) to evaluate the mechanism of diuretic action of kinin peptides in Malpighian tubules of the yellow fever mosquito Aedes aegypti. Now using the kinins of Aedes (the aedeskinins), we have found that in isolated Aedes Malpighian tubules all three aedeskinins (1 microM) significantly 1) increased the rate of fluid secretion (V(S)), 2) hyperpolarized the basolateral membrane voltage (V(bl)), and 3) decreased the input resistance (R(in)) of principal cells, consistent with the known increase in the Cl(-) conductance of the paracellular pathway in Aedes Malpighian tubules. Aedeskinin-III, studied in further detail, significantly increased V(S) with an EC(50) of 1.5 x 10(-8) M. In parallel, the Na(+) concentration in secreted fluid significantly decreased, and the K(+) concentration significantly increased. The concentration of Cl(-) remained unchanged. While the three aedeskinins triggered effects on V(bl), R(in), and V(S), synthetic kinin analogs, which contain modifications of the COOH-terminal amide pentapeptide core sequence critical for biological activity, displayed variable effects. For example, kinin analog 1578 significantly stimulated V(S) but had no effect on V(bl) and R(in), whereas kinin analog 1708 had no effect on V(S) but significantly affected V(bl) and R(in). These observations suggest separate signaling pathways activated by kinins. One triggers the electrophysiological response, and the other triggers fluid secretion. It remains to be determined whether the two signaling pathways emanate from a single kinin receptor via agonist-directed signaling or from a differentially glycosylated receptor. Occasionally, Malpighian tubules did not exhibit a detectable response to natural and synthetic kinins. Hypothetically, the expression of the kinin receptor may depend on developmental, nutritional, and/or reproductive signals.
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Affiliation(s)
- Stephen A Schepel
- Dept. of Biomedical Sciences, VRT 8004, Cornell Univ., Ithaca, NY 14853, USA
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Blumenthal EM. Isoform- and cell-specific function of tyrosine decarboxylase in the Drosophila Malpighian tubule. ACTA ACUST UNITED AC 2010; 212:3802-9. [PMID: 19915121 DOI: 10.1242/jeb.035782] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The biogenic amine tyramine (TA) is a potent diuretic factor when applied to the Malpighian tubule (MT) of Drosophila melanogaster, stimulating both urine production and transepithelial chloride conductance. Isolated MTs can respond not only to TA but also to its precursor, tyrosine; this observation led to the proposal that MTs are able to synthesize TA from applied tyrosine through the action of the enzyme tyrosine decarboxylase (TDC). In the current study it is shown that the non-neuronal isoform of TDC, Tdc1, is expressed in the principal cells of the MT. A mutant allele of Tdc1, Tdc1(f03311), was identified that reduced expression of the mature Tdc1 transcript by greater than 100-fold. MTs isolated from Tdc1(f03311) homozygous flies showed no significant depolarization of their transepithelial potential (TEP) or diuresis in response to tyrosine while retaining normal sensitivity to TA. By contrast, a previously identified null mutant allele of the neuronal TDC isoform Tdc2 had no effect on either tyrosine or TA sensitivity. To determine in which cell type of the MT Tdc1 expression is required, flies were generated carrying a UAS-Tdc1 transgene and cell-type-specific Gal4 drivers on a Tdc1(f03311) homozygous background. Rescue of Tdc1 expression in principal cells fully restored sensitivity to tyrosine whereas expression of Tdc1 in stellate cells had no rescuing effect. It is concluded that synthesis of TA by Tdc1 in the principal cells of the MT is required for physiological responses to tyrosine. TA synthesis in the MT is the first reported physiological role for Drosophila Tdc1.
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Affiliation(s)
- Edward M Blumenthal
- Department of Biological Sciences, Marquette University, P.O. Box 1881, Milwaukee, WI 53201-1881, USA.
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11
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Ruiz-Sanchez E, Orchard I, Lange AB. Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål). Toxicon 2010; 55:1162-70. [PMID: 20060849 DOI: 10.1016/j.toxicon.2010.01.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 12/31/2009] [Accepted: 01/05/2010] [Indexed: 10/20/2022]
Abstract
The production of peptide toxins by entomopathogenic fungi during the infection process plays critical roles in pathogenesis. To gain insight into the mechanism of action of these mycotoxins on insect internal organs, we have evaluated the effects of destruxin A, a cyclic peptide produced by Metarhizium anispliae, on Rhodnius prolixus Malpighian tubules measuring fluid secretion rate, transepithelial electrical potential (TEP), pH and ion composition of secreted fluid, and ATP content. Destruxin A dramatically inhibited fluid secretion rate on tubules stimulated by 5-Hydroxytryptamine (5-HT) or cAMP. The calculated IC(50) for destruxin A on 5-HT-stimulated tubules was 3 x 10(-7) M. Fluid secretion rate by Malpighian tubules exposed for 20 min to 10(-6) M destruxin A recovered completely when tubules were washed with saline; however, when tubules were exposed to 5 x 10(-6) M destruxin A the fluid secretion rate only partially recovered upon wash off. The use of Ca(2+)-free saline or addition of the calcium channel blocker CoCl(2) to the bathing saline did not interfere with the effects of destruxin A, and neither did the modification of intracellular calcium by TMB-8. Measurement of TEP of tubules challenged with 5-HT after preincubation for 10 min in saline containing 10(-6) M destruxin A showed that the second and third phases of the typical triphasic response to 5-HT were disrupted. Likewise, the positive shift in TEP in response to 5-HT in chloride-free bathing saline was significantly reduced when tubules were preincubated for 10 min in 10(-6) M destruxin A. The pH of the secreted fluid, but not the Na(+) or K(+) concentration, increased significantly when 5-HT-stimulated tubules were exposed to 10(-6) M destruxin A. The ATP content was not significantly different when tubules stimulated with 5-HT were exposed to destruxin A. Taken together, these results show that destruxin A, without interfering with the intracellular ATP production, strongly inhibits fluid secretion rate by the Malpighian tubules of R. prolixus. Changes in properties of the TEP suggest that one of the target sites for this peptide toxin might be associated with inhibition of the apical V-type H(+) ATPase of tubule cells.
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Affiliation(s)
- Esau Ruiz-Sanchez
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.
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12
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A K(+)/H (+) P-ATPase transport in the accessory cell membrane of the blowfly taste chemosensilla sustains the transepithelial potential. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2008; 194:981-8. [PMID: 18818932 DOI: 10.1007/s00359-008-0371-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/03/2008] [Accepted: 09/05/2008] [Indexed: 10/21/2022]
Abstract
An electrogenic K(+) transport in the tormogen cell of insect chemosensilla is involved in the generation and maintenance of the transepithelial potential (TEP). To gain more information about the K(+) transport system underlying the TEP generation and the location of its components in the plasma membrane of the tormogen cell, we studied the effects of inhibitors of K(+)/H(+) P-ATPase (bafilomycin A1, omeprazole and Na-orthovanadate), of K(+)/Cl(-) co-transport (bumetanide), of Cl(-) channels (NPPB) and of a K(+) channel blocker (BaCl(2)). The relationship between TEP amplitude and spike firing activity was also studied. Experiments were performed on the labellar chemosensilla of the blowfly Protophormia terraenovae using a modified tip-recording technique. Results show that: (a) K(+)/H(+) P-ATPase inhibitors significantly decrease the TEP, when properly applied to the labellum for 20 min, so as to reach the basolateral side of the plasma membrane, while no effect was detected when applied to the apical side, (b) bumetanide, NPPB and BaCl(2) decrease the TEP value only when administered to the apical side, (c) spike activity is positively correlated with the TEP. A model is proposed of the active and passive K(+) transports sustaining the TEP associated with the blowfly chemosensilla.
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Teets NM, Elnitsky MA, Benoit JB, Lopez-Martinez G, Denlinger DL, Lee RE. Rapid cold-hardening in larvae of the Antarctic midgeBelgica antarctica:cellular cold-sensing and a role for calcium. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1938-46. [DOI: 10.1152/ajpregu.00459.2007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In many insects, the rapid cold-hardening (RCH) response significantly enhances cold tolerance in minutes to hours. Larvae of the Antarctic midge, Belgica antarctica, exhibit a novel form of RCH, by which they increase their freezing tolerance. In this study, we examined whether cold-sensing and RCH in B. antarctica occur in vitro and whether calcium is required to generate RCH. As demonstrated previously, 1 h at −5°C significantly increased organismal freezing tolerance at both −15°C and −20°C. Likewise, RCH enhanced cell survival of fat body, Malpighian tubules, and midgut tissue of larvae frozen at −20°C. Furthermore, isolated tissues retained the capacity for RCH in vitro, as demonstrated with both a dye exclusion assay and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based viability assay, thus indicating that cold-sensing and RCH in B. antarctica occur at the cellular level. Interestingly, there was no difference in survival between tissues that were supercooled at −5°C and those frozen at −5°C, suggesting that temperature mediates the RCH response independent of the freezing of body fluids. Finally, we demonstrated that calcium is required for RCH to occur. Removing calcium from the incubating solution slightly decreased cell survival after RCH treatments, while blocking calcium with the intracellular chelator BAPTA-AM significantly reduced survival in the RCH treatments. The calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) also significantly reduced cell survival in the RCH treatments, thus supporting a role for calcium in RCH. This is the first report implicating calcium as an important second messenger in the RCH response.
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Coast GM, Nachman RJ, Schooley DA. An antidiuretic peptide (Tenmo-ADFb) with kinin-like diuretic activity on Malpighian tubules of the house cricket, Acheta domesticus (L.). ACTA ACUST UNITED AC 2008; 210:3979-89. [PMID: 17981866 DOI: 10.1242/jeb.006056] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Acheta domesticus is reported to have an antidiuretic hormone that reduces Malpighian tubule secretion. Identified peptides known to work in this way (Tenmo-ADFa and ADFb, and Manse-CAP(2b)) were tested as candidates for the unidentified hormone, along with their second messenger, cyclic GMP. Only Tenmo-ADFb was active, but was diuretic, as was 8-bromo cyclic GMP. The activity of Tenmo-ADFb is comparable to that of the cricket kinin neuropeptide, Achdo-KII, but it is much less potent. Its activity was unaffected by deleting either the six N-terminal residues or the C-terminal phenylalanine. At high concentrations, tubule secretion is doubled by Tenmo-ADFb and Achdo-KII, but their actions are non-additive, suggesting they have a similar mode of action. Both stimulate a non-selective KCl and NaCl diuresis, which is consistent with the opening of a transepithelial Cl(-) conductance. In support of this, the diuretic response to Tenmo-ADFb and Achdo-KII is prevented by a ten-fold reduction in bathing fluid chloride concentration, and both peptides cause the lumen-positive transepithelial voltage to collapse. The Cl(-) conductance pathway appears likely to be transcellular, because the Cl(-) channel blocker DPC reduces both basal and peptide-stimulated rates of secretion. The effects of 8-bromo cyclic GMP on transepithelial voltage and composition of the secreted fluid are markedly different from those of Tenmo-ADFb. This is the first report of the antidiuretic factor Tenmo-ADFb stimulating tubule secretion. Although the actions of Tenmo-ADFb are indistinguishable from those of Achdo-KII, it is unlikely to act at a kinin receptor, because the core sequence (residues 7-12) lacks the Phe and Trp residues that are critical for kinin activity.
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Affiliation(s)
- Geoffrey M Coast
- School of Biological and Chemical Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK.
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15
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Blumenthal EM. Modulation of tyramine signaling by osmolality in an insect secretory epithelium. Am J Physiol Cell Physiol 2005; 289:C1261-7. [PMID: 15987771 DOI: 10.1152/ajpcell.00026.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The control of water balance in multicellular organisms depends on absorptive and secretory processes across epithelia. This study concerns the effects of osmolality on the function of the Malpighian tubules (MTs), a major component of the insect excretory system. Previous work has shown that the biogenic amine tyramine increases transepithelial chloride conductance and urine secretion in Drosophila MTs. This study demonstrates that the response of MTs to tyramine, as measured by the depolarization of the transepithelial potential (TEP), is modulated by the osmolality of the surrounding medium. An increase in osmolality caused decreased tyramine sensitivity, whereas a decrease in osmolality resulted in increased tyramine sensitivity; changes in osmolality of +/-20% resulted in a nearly 10-fold modulation of the response to 10 nM tyramine. The activity of another diuretic agent, leucokinin, was similarly sensitive to osmolality, suggesting that the modulation occurs downstream of the tyramine receptor. In response to continuous tyramine signaling, as likely occurs in vivo, the TEP oscillates, and an increase in osmolality lengthened the period of these oscillations. Increased osmolality also caused a decrease in the rate of urine production; this decrease was attenuated by the tyraminergic antagonist yohimbine. A model is proposed in which this modulation of tyramine signaling enhances the conservation of body water during dehydration stress. The modulation of ligand signaling is a novel effect of osmolality and may be a widespread mechanism through which epithelia respond to changes in their environment.
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Affiliation(s)
- Edward M Blumenthal
- Department of Biological Sciences, Marquette University, PO Box 1881, Milwaukee, WI 53201-1881, USA.
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O'Donnell MJ, Rheault MR. Ion-selective microelectrode analysis of salicylate transport by the Malpighian tubules and gut ofDrosophila melanogaster. J Exp Biol 2005; 208:93-104. [PMID: 15601881 DOI: 10.1242/jeb.01374] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYTransport of the organic anion salicylate by the Malpighian tubules and gut of larval and adult fruit flies was studied using two salicylate-selective microelectrode methods. The first method combined the high selectivity of tridodecylmethylammonium-based electrodes for salicylate with the self-referencing ion-selective microelectrode technique for non-invasive spatial and temporal analysis of salicylate flux. Measurements with this technique revealed secretion of salicylate across the main and distal segments of the Malpighian tubule as well as the midgut, ileum and rectum. The second method used a salicylate-selective microelectrode to measure the concentration of salicylate in fluid droplets secreted by isolated DrosophilaMalpighian tubules set up in a Ramsay secretion assay. Transepithelial salicylate flux was calculated as the product of fluid secretion rate and secreted fluid salicylate concentration. Measurements with this method revealed that salicylate transport was active and saturable; the kinetic parameters Jmax and Kt were 2.72 pmol min-1 tubule-1 and 0.046 mmol l-1,respectively. Measurements of transepithelial salicylate flux determined by both microelectrode methods were in good agreement. Transepithelial flux measurements measured by microelectrodes were also validated by comparing them with measurements of radiolabelled salicylate levels in secreted droplets. Salicylate concentrations in haemolymph samples were measured with salicylate-selective microelectrodes after injection of salicylate into the haemocoel or after insects were fed salicylate-rich diets. The rate of salicylate secretion by Malpighian tubules in vitro was sufficient to account for the measured rate of decline of salicylate concentration in the haemolymph in vivo.
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Affiliation(s)
- Michael J O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1.
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Pollock VP, Radford JC, Pyne S, Hasan G, Dow JAT, Davies SA. NorpA and itpr mutants reveal roles for phospholipase C and inositol (1,4,5)- trisphosphate receptor in Drosophila melanogaster renal function. J Exp Biol 2003; 206:901-11. [PMID: 12547945 DOI: 10.1242/jeb.00189] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutants of norpA, encoding phospholipase C beta (PLC beta), and itpr, encoding inositol (1,4,5)-trisphosphate receptor (IP(3)R), both attenuate response to diuretic peptides of Drosophila melanogaster renal (Malpighian) tubules. Intact tubules from norpA mutants severely reduced diuresis stimulated by the principal cell- and stellate cell-specific neuropeptides, CAP(2b) and Drosophila leucokinin (Drosokinin), respectively, suggesting a role for PLC beta in both these cell types. Measurement of IP(3) production in wild-type tubules and in Drosokinin-receptor-transfected S2 cells stimulated with CAP(2b) and Drosokinin, respectively, confirmed that both neuropeptides elevate IP(3) levels. In itpr hypomorphs, basal IP(3) levels are lower, although CAP(2b)-stimulated IP(3) levels are not significantly reduced compared with wild type. However, CAP(2b)-stimulated fluid transport is significantly reduced in itpr alleles. Rescue of the itpr(90B.0) allele with wild-type itpr restores CAP(2b)-stimulated fluid transport levels to wild type. Drosokinin-stimulated fluid transport is also reduced in homozygous and heteroallelic itpr mutants. Measurements of cytosolic calcium levels in intact tubules of wild-type and itpr mutants using targeted expression of the calcium reporter, aequorin, show that mutations in itpr attenuated both CAP(2b)- and Drosokinin-stimulated calcium responses. The reductions in calcium signals are associated with corresponding reductions in fluid transport rates. Thus, we describe a role for norpA and itpr in renal epithelia and show that both CAP(2b) and Drosokinin are PLC beta-dependent, IP(3)-mobilising neuropeptides in Drosophila. IP(3)R contributes to the calcium signalling cascades initiated by these peptides in both principal and stellate cells.
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Affiliation(s)
- Valerie P Pollock
- Institute of Biomedical and Life Sciences, Division of Molecular Genetics, University of Glasgow, Glasgow G11 6NU, UK
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Blumenthal EM. Regulation of chloride permeability by endogenously produced tyramine in the Drosophila Malpighian tubule. Am J Physiol Cell Physiol 2003; 284:C718-28. [PMID: 12444020 DOI: 10.1152/ajpcell.00359.2002] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Malpighian (renal) tubule of Drosophila melanogaster is a useful model for studying epithelial transport. The purpose of this study was to identify factors responsible for modulating transepithelial chloride conductance in isolated tubules. I have found that tyrosine and several of its metabolites cause an increase in chloride conductance. The most potent of these agonists is tyramine, which is active at low nanomolar concentrations; the pharmacology of this response matches that of the previously published cloned insect tyramine receptor. In addition, the tubule appears capable of synthesizing tyramine from applied tyrosine, as shown by direct measurement of tyrosine decarboxylase activity. Immunohistochemical staining of tubules with an antibody against tyramine indicates that the principal cells are the sites of tyramine production, whereas previous characterization of the regulation of chloride conductance suggests that tyramine acts on the stellate cells. This is the first demonstration of a physiological role for an insect tyramine receptor.
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Affiliation(s)
- Edward M Blumenthal
- Department of Biology and Center for Biological Timing, University of Virginia, Charlottesville 22904-4328, USA.
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Hazel MH, Ianowski JP, Christensen RJ, Maddrell SHP, O'Donnell MJ. Amino acids modulate ion transport and fluid secretion by insect Malpighian tubules. J Exp Biol 2003; 206:79-91. [PMID: 12456699 DOI: 10.1242/jeb.00058] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Insect haemolymph typically contains very high levels of free amino acids. This study shows that amino acids can modulate the secretion of ions and water by isolated Malpighian tubules of Rhodnius prolixus and Drosophila melanogaster. Secretion rates of Rhodnius tubules in amino-acid-free saline increase after addition of serotonin to a peak value, then slowly decline to a plateau. Addition of glutamine, glutamate or aspartate to such tubules increases secretion rates dramatically relative to the controls in amino-acid-free saline, and these increases are sustained for 1-2 h. Seven other amino acids have more modest stimulatory effects, whereas lysine and arginine are inhibitory. Secreted fluid pH and Na(+) concentration increase and K(+) concentration decreases in response to glutamine. Pre-incubation of unstimulated tubules in saline solutions containing amino acids followed by stimulation with serotonin in amino-acid-free saline shows that the effects of amino acids far outlast the duration of exposure to them. Amino acids do not appear to be important as metabolites in Rhodnius tubules, nor do they act to draw significant amounts of water into the lumen by osmosis. Significant stimulation of fluid secretion can be achieved by physiological levels of particular amino acids, whereas those amino acids that inhibit fluid secretion only do so at concentrations much above those at which they occur naturally in the haemolymph. Secretion rates of unstimulated or stimulated Drosophila tubules are increased by pre-incubation in saline solutions containing glutamine or methionine or by continuous exposure to glutamine, methionine or tyrosine. Cysteine dramatically inhibited fluid secretion by Drosophila tubules, but only at concentrations well above the physiological range. We suggest that the amino acids probably function as compatible intracellular osmolytes that are necessary for sustained secretion at high rates by the Malpighian tubules.
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Affiliation(s)
- Matthew H Hazel
- Dept of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4KI, Canada
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Yu MJ, Beyenbach KW. Leucokinin activates Ca(2+)-dependent signal pathway in principal cells of Aedes aegypti Malpighian tubules. Am J Physiol Renal Physiol 2002; 283:F499-508. [PMID: 12167601 DOI: 10.1152/ajprenal.00041.2002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of Ca(2+) in mediating the diuretic effects of leucokinin-VIII was studied in isolated perfused Malpighian tubules of the yellow fever mosquito, Aedes aegypti. Peritubular leucokinin-VIII (1 microM) decreased the transepithelial resistance from 11.2 to 2.6 kOmega. cm, lowered the transepithelial voltage from 42.8 to 2.7 mV, and increased transepithelial Cl(-) diffusion potentials 5.1-fold. In principal cells of the tubules, leucokinin-VIII decreased the fractional resistance of the basolateral membrane from 0.733 to 0.518. These effects were reversed by the peritubular Ca(2+)-channel blocker nifedipine, suggesting a role of peritubular Ca(2+) and basolateral Ca(2+) channels in signal transduction. In Ca(2+)-free Ringer bath, the effects of leucokinin-VIII were partial and transient but were fully restored after the bath Ca(2+) concentration was restored. Increasing intracellular Ca(2+) with thapsigargin duplicated the effects of leucokinin-VIII, provided that peritubular Ca(2+) was present. The kinetics of the effects of leucokinin-VIII is faster than that of thapsigargin, suggesting the activation of inositol-1,4,5-trisphosphate-receptor channels of intracellular stores. Store depletion may then bring about Ca(2+) entry into principal cells via nifedipine-sensitive Ca(2+) channels in the basolateral membrane.
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Affiliation(s)
- Ming-Jiun Yu
- Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853, USA
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