|
|
||||||||
1 Renal Research Group, Institute of Medicine, University of Bergen, Bergen, Norway; and 2 Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7545
Previous studies
have demonstrated that arginine vasopressin (AVP) produces exaggerated
renal vasoconstriction in young spontaneously hypertensive rats (SHR)
relative to normotensive rats. The exaggerated renal vascular
reactivity does not appear to be due to a primary defect in
postreceptor calcium signal transduction. Although the magnitudes of
vascular responses differ, the relative proportions of calcium entry
and mobilization pathways evoked by AVP in renal resistance vessels are
similar in these rat strains. The purpose of the present study was to
evaluate possible differences in V1 mRNA and receptor
density and affinity in preglomerular resistance vessels (<50 µm)
obtained from young Wistar-Kyoto (WKY) and SHR. Quantitative RT-PCR
analysis revealed twofold greater expression of the V1a
receptor gene in preglomerular arterioles of 7-wk-old SHR compared with
WKY. In vitro radiolabeled ligand binding studies were performed under
equilibrium conditions on preglomerular resistance arterioles freshly
isolated from kidneys of 7-wk-old rats. The results indicate that AVP
receptor density (Bmax) is two to three times greater in
SHR than in WKY (248 ± 24 vs. 91 ± 11 fmol/mg protein,
P < 0.001). The affinity does not differ between strains (Kd = 0.5 nM). Displacement studies yielded similar
results for SHR and WKY. Unlabeled AVP completely displaced
[3H]AVP binding, with an IC50 of
2.5 × 10
10 M. Expression of AVP
receptor types in afferent arterioles was evaluated using the
V1 receptor agonist,
[Phe2, Ile3,Org8]vasopressin,
the V1 receptor antagonist,
[d(CH2)5, Tyr(Me)2,Tyr(NH2)9]Arg8-vasopressin,
and the V2 receptor agonist,
desamino-[D-Arg8]vasopressin. Both
the V1 agonist and antagonist displaced up to 90% of the
AVP binding with IC50 values of 4 × 10
8 and 8 × 10
7 M, respectively. The V2
receptor agonist was a weak inhibitor, displacing less than 15% of AVP
binding at a high concentration of 10
4
M. These results demonstrate that virtually all AVP receptors in the
preglomerular arterioles are of the V1 type. Collectively, our results provide evidence that the enhanced renal reactivity to AVP
is mediated by a higher density of V1 receptors associated with increased gene expression in renal resistance vessels of SHR
developing genetic hypertension.
renal circulation; vascular resistance; afferent arteriole; glomerulus; vasopressin; spontaneously hypertensive rat; Wistar-Kyoto rat
This article has been cited by other articles:
![]() |
M. Hultstrom, F. Helle, and B. M. Iversen AT1 receptor activation regulates the mRNA expression of CAT1, CAT2, arginase-1, and DDAH2 in preglomerular vessels from angiotensin II hypertensive rats Am J Physiol Renal Physiol, July 1, 2009; 297(1): F163 - F168. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Helle, M. Hultstrom, T. Skogstrand, F. Palm, and B. M. Iversen Angiotensin II-induced contraction is attenuated by nitric oxide in afferent arterioles from the nonclipped kidney in 2K1C Am J Physiol Renal Physiol, January 1, 2009; 296(1): F78 - F86. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. B. Vagnes, B. M. Iversen, and W. J. Arendshorst Short-term ANG II produces renal vasoconstriction independent of TP receptor activation and TxA2/isoprostane production Am J Physiol Renal Physiol, September 1, 2007; 293(3): F860 - F867. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. B. Vagnes, F. H. Hansen, J. J. Feng, B. M. Iversen, and W. J. Arendshorst Enhanced Ca2+ response to AVP in preglomerular vessels from rats with genetic hypertension during different hydration states Am J Physiol Renal Physiol, June 1, 2005; 288(6): F1249 - F1256. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. H. Hansen, O. B. Vagnes, and B. M. Iversen Enhanced response to AVP in the interlobular artery from the spontaneously hypertensive rat Am J Physiol Renal Physiol, May 1, 2005; 288(5): F1023 - F1031. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. B. Vagnes, F. H. Hansen, R. E. F. Christiansen, C. Gjerstad, and B. M. Iversen Age-dependent regulation of vasopressin V1a receptors in preglomerular vessels from the spontaneously hypertensive rat Am J Physiol Renal Physiol, May 1, 2004; 286(5): F997 - F1003. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |