title: Vasopressin constricts outer medullary descending vasa recta isolated from rat kidneys.
abstract: 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 V1a-receptors. Ablumenal AVP (10(-10)-10(-6)M) or the selective V1a-receptor agonist [Phe2, Ile3, Orn8]-vasopressin (PO-VT, 10(-8) M) constricted OMDVR focally and (at higher AVP concentrations) transiently. The V1b agonist ideamino-Cys1,D-3-(pyridyl)Ala2,Arg8)vasopressin (DP-VP; 10(-8) M) and the V2 agonist [deamino-Cys1, D-Arg8]vasopressin (DDAVP; 10(-8) M) did not constrict OMDVR. The V1a antagonist [d(CH2)5(1), O-Me-Tyr2,Arg8]vasopressin (CTM-VP, 10(-10) 10(-8) M) inhibited vasoconstriction by AVP 10(-9 M), whereas the V2 antagonist [d(CH2)5(1), D-Ile2,Ile4 Arg8]vasopressin (II-VP) at low concentration (10(-10) M) did not. V2 stimulation seems to inhibit V1a constriction of OMDVR. DDAVP prevented constriction by PO-VT (10(-8) M) applied at the same time and dilated OMDVR preconstricted with PO-VT.
authors.affiliation: Nephrology Division, University of Maryland School of Medicine, Baltimore 21201-1595, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Turner
authors.forename: T L
authors.initials: TL
authors.lastname: Pallone
mesh_terms: D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000098:blood supply; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D017483:Receptors, Vasopressin / Q000819:agonists / Q000502:physiology; D012079:Renal Circulation / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D017483:Receptors, Vasopressin; D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin