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This Article Full Text Full Text (PDF) All Versions of this Article: 285/3/F507    most recent 00430.2002v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Helou, C. M. B. Articles by Marchetti, J. Search for Related Content PubMed PubMed Citation Articles by Helou, C. M. B. Articles by Marchetti, J.

Angiotensin receptor subtypes in thin and muscular juxtamedullary efferent arterioles of rat kidney

¹Institut National de la Santé et de la Recherche Médicale Unité 367, Physiologie et Pathologie Expérimentale Vasculaires, Université Paris VI, 75005 Paris; and ²Laboratoire de Biologie Intégrée des Cellules Rénales, Unité de Recherche Associée 1859 au Centre National de la Recherche Scientifique, Commissariat a l'Energie Atomique-Saclay, 91191 Gif-sur-Yvette, France

Submitted 19 December 2002 ; accepted in final form 2 May 2003

ANG II controls the vascular tone of pre- and postglomerular arterioles, and thereby glomerular filtration, through binding to either AT_1A, AT_1B, 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 AT_1A, AT_1B, 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 AT_1A, AT_1B, and AT₂ receptors, whereas thin arterioles only express the AT_1A 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.

angiotensin II; valsartan; calcium signaling

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