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Park S, Bivona BJ, Harrison-Bernard LM. Lack of contribution of nitric oxide synthase to cholinergic vasodilation in murine renal afferent arterioles. Am J Physiol Renal Physiol 2018; 314:F1197-F1204. [PMID: 29412691 DOI: 10.1152/ajprenal.00433.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously reported significant increases in neuronal nitric oxide synthase (NOS) immunostaining in renal arterioles of angiotensin type 1A receptor (AT1A) knockout mice, and in arterioles and macula densa cells of AT1A/AT1B knockout mice. The contribution of nitric oxide derived from endothelial and macula densa cells in the maintenance of afferent arteriolar tone and acetylcholine-induced vasodilation was functionally determined in kidneys of wild-type, AT1A, and AT1A/AT1B knockout mice. Acetylcholine-induced changes in arteriolar diameters of in vitro blood-perfused juxtamedullary nephrons were measured during control conditions, in the presence of the nonspecific NOS inhibitor, Nω-nitro-l-arginine methyl ester (NLA), or the highly selective neuronal NOS inhibitor, N5-(1-imino-3-butenyl)-l-ornithine (VNIO). Acetylcholine (0.1 mM) produced a significant vasoconstriction in afferent arterioles of AT1A/AT1B mice (-10.9 ± 5.1%) and no changes in afferent arteriolar diameters of AT1A knockout mice. NLA (0.01-1 mM) or VNIO (0.01-1 μM) induced significant dose-dependent vasoconstrictions (-19.8 ± 4.0% 1 mM NLA; -7.8 ± 3.5% 1 μM VNIO) in afferent arterioles of kidneys of wild-type mice. VNIO had no effect on afferent arteriole diameters of AT1A knockout or AT1A/AT1B knockout mice, suggesting nonfunctional neuronal nitric oxide synthase. These data indicate that acetylcholine produces a significant renal afferent arteriole vasodilation independently of nitric oxide synthases in wild-type mice. AT1A receptors are essential for the manifestation of renal afferent arteriole responses to neuronal nitric oxide synthase-mediated nitric oxide release.
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Affiliation(s)
- Sungmi Park
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Benjamin J Bivona
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Lisa M Harrison-Bernard
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana
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2
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Chollet C, Placier S, Chatziantoniou C, Hus-Citharel A, Caron N, Roussel R, Alhenc-Gelas F, Bouby N. Genetically increased angiotensin I-converting enzyme alters peripheral and renal vascular reactivity to angiotensin II and bradykinin in mice. Am J Physiol Heart Circ Physiol 2018; 314:H350-H358. [DOI: 10.1152/ajpheart.00356.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Angiotensin I-converting enzyme (ACE) levels in humans are under strong genetic influence. Genetic variation in ACE has been linked to risk for and progression of cardiovascular and renal diseases. Causality has been documented in genetically modified mice, but the mechanisms underlying causality are not completely elucidated. To further document the vascular and renal consequences of a moderate genetic increase in ACE synthesis, we studied genetically modified mice carrying three copies of the ACE gene (three-copy mice) and littermate wild-type animals (two-copy mice). We investigated peripheral and renal vascular reactivity to angiotensin II and bradykinin in vivo by measuring blood pressure and renal blood flow after intravenous administration and also reactivity of isolated glomerular arterioles by following intracellular Ca2+ mobilization. Carrying three copies of the ACE gene potentiated the systemic and renal vascular responses to angiotensin II over the whole range of peptide concentration tested. Consistently, the response of isolated glomerular afferent arterioles to angiotensin II was enhanced in three-copy mice. In these mice, signaling pathways triggered by endothelial activation by bradykinin or carbachol in glomerular arterioles were also altered. Although the nitric oxide (NO) synthase (NOS)/NO pathway was not functional in arterioles of two-copy mice, in muscular efferent arterioles of three-copy mice NOS3 gene expression was induced and NO mediated the effect of bradykinin or carbachol. These data document new and unexpected vascular consequences of a genetic increase in ACE synthesis. Enhanced vasoconstrictor effect of angiotensin II may contribute to the risk for cardiovascular and renal diseases linked to genetically high ACE levels. NEW & NOTEWORTHY A moderate genetic increase in angiotensin I-converting enzyme (ACE) in mice similar to the effect of the ACE gene D allele in humans unexpectedly potentiates the systemic and renal vasoconstrictor responses to angiotensin II. It also alters the endothelial signaling pathways triggered by bradykinin or carbachol in glomerular efferent arterioles.
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Affiliation(s)
- Catherine Chollet
- Institut National de la Santé Et de la Recherche Medicale (INSERM) U1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre and Marie Curie, Paris, France
- Université Paris Descartes, Paris, France
| | - Sandrine Placier
- Université Pierre and Marie Curie, Paris, France
- INSERM, UMRS 1155, Hopital Tenon, Paris, France
| | - Christos Chatziantoniou
- Université Pierre and Marie Curie, Paris, France
- INSERM, UMRS 1155, Hopital Tenon, Paris, France
| | - Annette Hus-Citharel
- College de France, Center for Interdisciplinary Research in Biology, INSERM U1050, Paris, France
| | - Nathalie Caron
- Université de Namur, Faculté de Medecine, Namur, Belgium
| | - Ronan Roussel
- Institut National de la Santé Et de la Recherche Medicale (INSERM) U1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre and Marie Curie, Paris, France
- Université Paris Descartes, Paris, France
- Université Paris Diderot, Paris, France
- Department of Diabetology-Endocrinology-Nutrition, DHU FIRE, Bichat Hospital, AP-HP, Paris, France
| | - François Alhenc-Gelas
- Institut National de la Santé Et de la Recherche Medicale (INSERM) U1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre and Marie Curie, Paris, France
- Université Paris Descartes, Paris, France
| | - Nadine Bouby
- Institut National de la Santé Et de la Recherche Medicale (INSERM) U1138, Centre de Recherche des Cordeliers, Paris, France
- Université Pierre and Marie Curie, Paris, France
- Université Paris Descartes, Paris, France
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3
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El-Gowelli HM, El-Gowilly SM, Elsalakawy LK, El-Mas MM. Nitric oxide synthase/K+ channel cascade triggers the adenosine A(2B) receptor-sensitive renal vasodilation in female rats. Eur J Pharmacol 2013; 702:116-25. [PMID: 23396225 DOI: 10.1016/j.ejphar.2013.01.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 01/17/2013] [Accepted: 01/29/2013] [Indexed: 01/02/2023]
Abstract
Adenosine A2B-receptors mediate the adenosine-evoked renal vasodilations in male rats. Here, we tested whether this finding could be replicated in female renal vasculature and whether K(+) hyperpolarization induced by nitric oxide synthase (NOS) and/or heme oxygenase (HO) accounts for adenosine A2B receptor-sensitive renal vasodilations. In phenylephrine-preconstricted perfused kidneys, vasodilations caused by the adenosine analog 5'-N-ethylcarboxamidoadenosine (NECA, 1.6-50 nmol) were attenuated after blockade of adenosine A2B (alloxazine) but not A2A [8-(3-Chlorostyryl) caffeine, CSC] or A3 receptors (N-(2-methoxyphenyl)-N'-[2-(3-pyridinyl)-4-quinazolinyl]-urea, VUF 5574), confirming the preferential involvement of A2B receptors in NECA responses. NOS activation mediated the A2B receptor-mediated NECA response because: (i) NOS inhibition (N(ω)-nitro-L-arginine-methyl ester, L-NAME) attenuated NECA vasodilations, (ii) concurrent L-NAME/alloxazine exposure caused more inhibition of NECA responses, and (iii) inhibition of NECA responses by alloxazine disappeared in L-arginine-supplemented preparations. Although HO inhibition (zinc protoporphyrin) failed to modify NECA responses, the attenuation of these responses by alloxazine disappeared in hemin (HO inducer)-treated preparations. NECA vasodilations were also attenuated after exposure to BaCl2, glibenclamide but not tetraethylammonium (blockers of inward rectifier, ATP-sensitive, and Ca(2+)-dependent K(+)-channels, respectively). The combined alloxazine/BaCl2/glibenclamide infusion caused no additional attenuation of NECA vasodilations. Vasodilations caused by minoxidil (K(+)-channel opener) were reduced by L-NAME or BaCl2/glibenclamide, supporting the importance of NOS signaling in K(+) hyperpolarization. NECA or minoxidil vasodilations were attenuated by ouabain, Na(+)/K(+)-ATPase inhibitor, and in KCl-preconstricted preparations. Overall, facilitation of adenosine A2B receptor/NOS/K(+) channel/Na(+)/K(+)-ATPase cascade underlies NECA vasodilations in female rats. Enhancing HO activity, albeit not causally related to NECA vasodilations, improves the pharmacologically compromised (alloxazine) NECA response.
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Affiliation(s)
- Hanan M El-Gowelli
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
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5
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de Wit C, Griffith TM. Connexins and gap junctions in the EDHF phenomenon and conducted vasomotor responses. Pflugers Arch 2010; 459:897-914. [PMID: 20379740 DOI: 10.1007/s00424-010-0830-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 03/16/2010] [Indexed: 12/21/2022]
Abstract
It is becoming increasingly evident that electrical signaling via gap junctions plays a central role in the physiological control of vascular tone via two related mechanisms (1) the endothelium-derived hyperpolarizing factor (EDHF) phenomenon, in which radial transmission of hyperpolarization from the endothelium to subjacent smooth muscle promotes relaxation, and (2) responses that propagate longitudinally, in which electrical signaling within the intimal and medial layers of the arteriolar wall orchestrates mechanical behavior over biologically large distances. In the EDHF phenomenon, the transmitted endothelial hyperpolarization is initiated by the activation of Ca(2+)-activated K(+) channels channels by InsP(3)-induced Ca(2+) release from the endoplasmic reticulum and/or store-operated Ca(2+) entry triggered by the depletion of such stores. Pharmacological inhibitors of direct cell-cell coupling may thus attenuate EDHF-type smooth muscle hyperpolarizations and relaxations, confirming the participation of electrotonic signaling via myoendothelial and homocellular smooth muscle gap junctions. In contrast to isolated vessels, surprisingly little experimental evidence argues in favor of myoendothelial coupling acting as the EDHF mechanism in arterioles in vivo. However, it now seems established that the endothelium plays the leading role in the spatial propagation of arteriolar responses and that these involve poorly understood regenerative mechanisms. The present review will focus on the complex interactions between the diverse cellular signaling mechanisms that contribute to these phenomena.
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Affiliation(s)
- Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany.
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Compr Physiol 2008. [DOI: 10.1002/cphy.cp020413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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8
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00015-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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9
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Cao C, Goo JH, Lee-Kwon W, Pallone TL. Vasa recta pericytes express a strong inward rectifier K+ conductance. Am J Physiol Regul Integr Comp Physiol 2006; 290:R1601-7. [PMID: 16439665 DOI: 10.1152/ajpregu.00877.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Strong inward rectifier potassium channels are expressed by some vascular smooth muscle cells and facilitate K+-induced hyperpolarization. Using whole cell patch clamp of isolated descending vasa recta (DVR), we tested whether strong inward rectifier K+ currents are present in smooth muscle and pericytes. Increasing extracellular K+ from 5 to 50 and 140 mmol/l induced inward rectifying currents. Those currents were Ba2+ sensitive and reversed at the K+ equilibrium potential imposed by the electrode and extracellular buffers. Ba2+ binding constants in symmetrical K+ varied between 0.24 and 24 micromol/l at -150 and -20 mV, respectively. Ba2+ blockade was time and voltage dependent. Extracellular Cs+ also blocked the inward currents with binding constants between 268 and 4,938 micromol/l at -150 and -50 mV, respectively. Ba2+ (30 micromol/l) and ouabain (1 mmol/l) depolarized pericytes by an average of 11 and 24 mV, respectively. Elevation of extracellular K+ from 5 to 10 mmol/l hyperpolarized pericytes by 6 mV. That hyperpolarization was reversed by Ba2+ (30 micromol/l). We conclude that strong inward rectifier K+ channels and Na+-K+-ATPase contribute to resting potential and that KIR channels can mediate K+-induced hyperpolarization of DVR pericytes.
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Affiliation(s)
- Chunhua Cao
- Division of Nephrology, Department of Medicine, N3W143, 22 S. Greene St., University of Maryland, School of Medicine, Baltimore, MD 21201, USA
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Griffith TM. Endothelium-dependent smooth muscle hyperpolarization: do gap junctions provide a unifying hypothesis? Br J Pharmacol 2005; 141:881-903. [PMID: 15028638 PMCID: PMC1574270 DOI: 10.1038/sj.bjp.0705698] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
An endothelium-derived hyperpolarizing factor (EDHF) that is distinct from nitric oxide (NO) and prostanoids has been widely hypothesized to hyperpolarize and relax vascular smooth muscle following stimulation of the endothelium by agonists. Candidates as diverse as K(+) ions, eicosanoids, hydrogen peroxide and C-type natriuretic peptide have been implicated as the putative mediator, but none has emerged as a 'universal EDHF'. An alternative explanation for the EDHF phenomenon is that direct intercellular communication via gap junctions allows passive spread of agonist-induced endothelial hyperpolarization through the vessel wall. In some arteries, eicosanoids and K(+) ions may themselves initiate a conducted endothelial hyperpolarization, thus suggesting that electrotonic signalling may represent a general mechanism through which the endothelium participates in the regulation of vascular tone.
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Affiliation(s)
- Tudor M Griffith
- Department of Diagnostic Radiology, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN.
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Matsuda H, Hayashi K, Wakino S, Kubota E, Honda M, Tokuyama H, Takamatsu I, Tatematsu S, Saruta T. Role of Endothelium-Derived Hyperpolarizing Factor in ACE Inhibitor-Induced Renal Vasodilation in Vivo. Hypertension 2004; 43:603-9. [PMID: 14769805 DOI: 10.1161/01.hyp.0000118053.42262.71] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although the angiotensin-converting enzyme (ACE) inhibitor-induced bradykinin enhances nitric oxide (NO) release, bradykinin may also stimulate the production of an additional vasodilator, endothelium-derived hyperpolarizing factor (EDHF). This study examined the role of EDHF in mediating the NO-independent action of ACE inhibitors in canine renal microcirculation in vivo. We used intravital CCD camera videomicroscopy that allowed direct visualization of renal microcirculation in superficial and juxtamedullary nephrons in an in vivo, in situ, and relatively intact setting. In the presence of E4177 (an angiotensin receptor blocker), cilazaprilat (30 μg/kg) had no effect on diameter of superficial afferent arterioles (Aff), but it increased renal contents of bradykinin and nitrate plus nitrite, and it elicited dilation of juxtamedullary Aff (from 24.0±0.2 to 28.2±0.8 μm), juxtamedullary efferent arterioles (Eff) (from 24.2±0.2 to 28.0±0.8 μm), and superficial Eff (from 18.2±0.2 to 19.7±0.2 μm). These changes in diameters were prevented by N
α
-adamantaneacetyl-
d
-Arg-[Hyp
3
,Thi
5,8
,D-Phe
7
]bradykinin, a bradykinin receptor antagonist. The pretreatment with nitro-
l
-arginine methylester (
l
-NAME) plus E4177 eliminated the dilator response of juxtamedullary/superficial Eff and the increase in renal nitrate plus nitrite levels induced by cilazaprilat. In contrast, in the presence of E4177+
l-
NAME, cilazaprilat still caused 8%±3% dilation of juxtamedullary Aff, which was completely eliminated by proadifen, a cytochrome-P450 and K
Ca
channel blocker. Collectively, the ACE inhibitor exerts multiple vasodilator mechanisms, including the inhibition of angiotensin II formation; blockade of angiotensin II activity appears to be a dominant mechanism in superficial Aff, whereas the bradykinin-induced NO acts on superficial Eff and juxtamedullary Aff/Eff. Furthermore, a putative EDHF is an additional mechanism for the ACE inhibitor-induced vasodilation of juxtamedullary Aff in vivo.
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Affiliation(s)
- Hiroto Matsuda
- Department of Internal Medicine School of Medicine, Keio University, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan.
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Jerkic M, Rivas-Elena JV, Prieto M, Carrón R, Sanz-Rodríguez F, Pérez-Barriocanal F, Rodríguez-Barbero A, Bernabéu C, López-Novoa JM. Endoglin regulates nitric oxide‐dependent vasodilatation. FASEB J 2004; 18:609-11. [PMID: 14734648 DOI: 10.1096/fj.03-0197fje] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Endoglin is a membrane glycoprotein that plays an important role in cardiovascular development and angiogenesis. We examined the role of endoglin in the control of vascular tone by measuring nitric oxide (NO)-dependent vasodilation in haploinsufficient mice (Eng+/-) and their Eng+/+ littermates. The vasodilatory effect of acetylcholine, bradykinin, and sodium nitroprusside was assessed in anesthetized mice; in isolated, perfused hindlimbs; and in aortic rings. The substantial hypotensive and vasodilatory response induced by acetylcholine and bradykinin in Eng+/+ was markedly reduced in Eng+/- mice. Both kinds of animals had similar responses to sodium nitroprusside, suggesting that the deficient vasodilatory effect is not due to a NO response impairment. Urinary and plasma concentrations of nitrites, a NO metabolite, were lower in Eng+/- than in Eng+/+ mice. The levels of endothelial nitric oxide synthase (eNOS) in kidneys and femoral arteries were about half in Eng+/- than in Eng+/+ mice and were also reduced in primary cultures of aortic endothelial cells from Eng+/- compared with those from Eng+/+ mice. Furthermore, overexpression or suppression of endoglin in cultured cells induced a marked increase or decrease in the protein levels of eNOS, respectively. Thus, our results in vivo and in vitro demonstrate a relationship between endoglin and NO-dependent vasodilation mediated by the regulation of eNOS expression.
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Affiliation(s)
- Mirjana Jerkic
- Instituto Reina Sofía de Investigación Nefrológica, Departamento de Fisiología & Farmacología, Universidad de Salamanca, Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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Helou CMB, Imbert-Teboul M, Doucet A, Rajerison R, Chollet C, Alhenc-Gelas F, Marchetti J. Angiotensin receptor subtypes in thin and muscular juxtamedullary efferent arterioles of rat kidney. Am J Physiol Renal Physiol 2003; 285:F507-14. [PMID: 12734102 DOI: 10.1152/ajprenal.00430.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ANG II controls the vascular tone of pre- and postglomerular arterioles, and thereby glomerular filtration, through binding to either AT1A, AT1B, or AT2 receptors. AT1 receptors, which are coupled to intracellular Ca2+ signaling, have vasoconstricting effects, whereas AT2 receptors, whose signaling mechanism is unknown, induce vasodilatation. The angiotensin receptors have been characterized in afferent arterioles, which express the three types of receptors, but not in efferent arterioles. Two subpopulations of juxtamedullary efferent arterioles, muscular ones which terminate as vasa rectae and thin ones which terminate as peritubular capillaries, have been described. They display functional heterogeneity with regard to the ANG II response. To evaluate whether these differences are associated with differential expression of ANG II receptors, we examined the expression pattern of AT1A, AT1B, and AT2 receptor mRNAs by RT-PCR in these arterioles and studied the effect of valsartan, a specific AT1-receptor antagonist. Results indicate that muscular arterioles express AT1A, AT1B, and AT2 receptors, whereas thin arterioles only express the AT1A and AT2 types, and at a much lower level. Valsartan fully inhibited ANG II-induced increases in intracellular Ca2+ in both arteriolar types, but with different kinetics. In muscular arterioles, inhibition was monoexponential, whereas it displayed a marked positive cooperativity in thin arterioles. Finally, the apparent affinity for valsartan was higher in muscular than in thin arterioles. In conclusion, this study further documents the differences between muscular and thin efferent arterioles with regard to ANG II signalization in the rat kidney.
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Affiliation(s)
- Claudia M B Helou
- Institut National de la Santé et de la Recherche Médicale Unité 367, Physiologie et Pathologie Expérimentale Vasculaires, Université Paris VI, Paris, France
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Marchetti J, Helou CMB, Chollet C, Rajerison R, Alhenc-Gelas F. ACE and non-ACE mediated effect of angiotensin I on intracellular calcium mobilization in rat glomerular arterioles. Am J Physiol Heart Circ Physiol 2003; 284:H1933-41. [PMID: 12586636 DOI: 10.1152/ajpheart.00042.2003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Because renin and angiotensin I (ANG I) level are high in the renal circulation, the conversion of ANG I is a critical step in the regulation of glomerular hemodynamics. We studied this conversion by investigating the effect of ANG I on intracellular Ca(2+) concentration ([Ca(2+)](i)) in rat juxtamedullary glomerular afferent and efferent arterioles (AA and EA, respectively). Two types of EA were considered, thin EA and muscular EA, terminating as peritubular capillaries and vasa rectae, respectively. In all arterioles, ANG I elicited [Ca(2+)](i) elevations. Maximal responses of 171 +/- 28 (AA), 183 +/- 7 (muscular EA), and 78 +/- 11 nM (thin EA) (n = 6), similar to those obtained with ANG II, were observed with 100 nM ANG I. The EC(50) values were 20 times higher for ANG I than for ANG II in AA (10.2 vs. 0.5) and muscular EA (6.8 vs. 0.4 nM) and 150 times higher in thin EA (15.2 vs. 0.1 nM). ANG I effect was blocked by losartan, indicating that AT(1) receptors were involved. The ANG-converting enyzme (ACE) inhibitor lisinopril inhibited the maximal response to ANG I in AA and muscular EA by 75 +/- 9% (n = 13) and 70 +/- 7% (n = 13), respectively, but had no effect in thin EA (n = 14). The serine protease inhibitor aprotinin, the chymase inhibitor chymostatin, and the cysteine protease inhibitors E64 and leupeptin had no effect on ANG I action. These data show that ANG I effects are mainly mediated by ACE in AA and muscular EA but not in thin EA. The lisinopril-insensitive response may be related to conversion by unknown enzyme(s) and/or to activation of AT(1) receptors by ANG I.
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Affiliation(s)
- Jeannine Marchetti
- Institut National de la Santé et de la Recherche Médicale Unité 367, Physiologie et Pathologie Expérimentale Vasculaires, Université Paris VI, France.
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Borges AC, Feres T, Vianna LM, Paiva TB. Cholecalciferol treatment restores the relaxant responses of spontaneously hypertensive rat arteries to bradykinin. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2002; 8:263-268. [PMID: 12100972 DOI: 10.1016/s0928-4680(02)00036-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The vasodilation and hyperpolarization induced by bradykinin (BK) in the mesenteric vascular bed and mesenteric arteries from spontaneously hypertensive rats (SHR) and from normotensive Wistar rats (NWR), as well as Wistar Kyoto rats (WKY), was investigated before and after prolonged oral treatment with cholecalciferol (125 mg kg(-1) body weight per day) for 3 weeks. The cholecalciferol treatment caused a decrease in the SHR blood pressure, as well as a normalization in the resting potential of the smooth muscle cell membrane of mesenteric arteries and restored their hyperpolarizing response to BK. The concentration-response curves for the vasodilator effect of BK on the mesenteric vascular bed were significantly decreased in SHR and in WKY when compared with NWR. Cholecalciferol treatment improved the maximum responses of the SHR preparation, bringing them to levels similar to those of the NWR preparations, which themselves were unaffected by the treatment. In the presence of apamin, a Ca(2+)-dependent K(+) channel inhibitor, the maximum responses to BK in preparations from NWR or cholecalciferol-treated SHR decreased to values similar to those observed in untreated SHR. Our results indicate that the low responsivity of the SHR resistance vessels to the relaxant effect of BK is due to impaired Ca(2+)-dependent K(+) channels and that reversion of this impairment contributes to the blood pressure reduction caused by the cholecalciferol treatment. However, the mechanism of the low responsivity in WKY remains to be investigated.
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Affiliation(s)
- Antonio C.R. Borges
- Department of Biophysics, Universidade Federal de São Paulo, Rua Botucatu 862, 04023-062, SP, São Paulo, Brazil
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Wang X, Loutzenhiser R. Determinants of renal microvascular response to ACh: afferent and efferent arteriolar actions of EDHF. Am J Physiol Renal Physiol 2002; 282:F124-32. [PMID: 11739120 DOI: 10.1152/ajprenal.0157.2001] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renal microvascular actions of ACh were investigated using the in vitro perfused hydronephrotic rat kidney. ACh reversed ANG II-induced vasoconstriction in the afferent and efferent arteriole by 106 +/- 2 and 75 +/- 5%, respectively. Inhibition of nitric oxide synthase [NOS; 100 micromol/l N(G)-nitro-L-arginine methyl ester (L-NAME)] and cyclooxygenase (COX; 10 micromol/l ibuprofen) prevented the sustained response of the afferent arteriole but did not reduce the magnitude of the initial dilation (97 +/- 7%). However, NOS/COX inhibition abolished the response of the efferent arteriole. The underlying mechanisms mediating this endothelium-derived hyperpolarizing factor (EDHF)-like response were characterized using K channel blockers. Ba (100 micromol/l), tetraethylammonium (1 mmol/l), and ouabain (3 mmol/l) had no effect, arguing against a role of an inward rectifier K channel, large-conductance Ca-activated K channel, or Na,K-ATPase. Charybdotoxin (10 nmol/l) and apamin (1.0micromol/l) attenuated the response when administered alone (63 +/- 7% and 37 +/- 5%, respectively) and abolished the response when coadministered (0.1 +/- 1.0%). These findings indicate that, as in other vascular beds, the renal EDHF-like response to ACh involves K channels that are sensitive to a combination of apamin and charybdotoxin. Our finding that EDHF modulates preglomerular, but not postglomerular, tone is consistent with the evolving concept that vasomotor mechanisms in cortical efferent arterioles do not involve voltage-gated Ca entry.
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Affiliation(s)
- Xuemei Wang
- Smooth Muscle Research Group, Department of Pharmacology and Therapeutics, University of Calgary, Calgary, Alberta, Canada
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