Vasopressin constricts outer medullary descending vasa recta
isolated from rat kidneys .
Turner, Malcolm R., and Thomas L. Pallone.
Nephrology Division, University of Maryland School of Medicine,
Baltimore,
APStracts 3:0193F, 1996.
Vasopressin constricts outer medullary descending vasa recta isolated
from rat kidneys. Arginine vasopressin (AVP) can selectively decrease
blood flow in the renal medulla, but the sites of vasoconstriction
are uncertain. We have examined the effects of vasopressin-receptor
agonists and antagonists on the diameters of outer medullary
descending vasa recta (OMDVR), isolated and perfused in vitro . AVP
can constrict OMDVR, apparently via V 1a receptors. Ablumenal AVP (10
-10 to 10 -6 M) or the selective V 1a receptor agonist [Phe 2 , Ile 3
, Orn 8 ]-vasopressin (PO-VT; 10 -8 M) constricted OMDVR focally and
(at higher AVP concentrations) transiently. The V 1b agonist
[deamino-Cys 1 , D-3-(Pyridyl)Ala 2 , Arg 8 ]-vasopressin (DP-VP; 10
-8 M) and the V 2 agonist [deamino-Cys 1 , D-Arg 8 ]-vasopressin
(dDAVP; 10 -8 M) did not constrict OMDVR. The V 1a antagonist d(CH 2
) 5 1 , O-Me-Tyr 2 , Arg 8 ]-vasopressin (CTM-VP; 10 -10 or 10 -8 M)
inhibited vasoconstriction by AVP (10 -9 M), whereas the V 2
antagonist [d(CH 2 ) 5 1 , D-Ile 2 , Ile 4 , Arg 8 ]-vasopressin (II
-VP) at low concentration (10 -10 M) did not. V 2 stimulation seems to
inhibit V 1a constriction of OMDVR. dDAVP prevented constriction by
PO-VT (10 -8 M) applied at the same time and dilated OMDVR
preconstricted with PO-VT.
Received 9 August 1996; accepted in final form 17 October 1996.
APS Manuscript Number F230-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996