Faculty Collaboration Database

Renal cortical and medullary blood flow responses during water restriction: role of vasopressin. Am J Physiol 1996 Jun;270(6 Pt 2):R1257-64

Date

06/11/1996

Pubmed ID

8764292

DOI

10.1152/ajpregu.1996.270.6.R1257

Scopus ID

2-s2.0-0029801794 (requires institutional sign-in at Scopus site)   65 Citations

Abstract

Experiments were performed in unanesthetized rats to determine responses to 48 h water restriction of the renal regional microcirculation (cortex, outer medulla, and inner medulla) using implanted optical fibers and laser-Doppler flowmetry. The role of vasopressin (AVP) as a mediator of renal regional blood low changes and its contribution to urinary concentrating ability were assessed by continuous intramedullary interstitial infusion of specific V1 receptor antagonist d(CH2)5 [Tyr-(Me)2, Ala-NH2]AVP (2ng . kg-1 . min-1). Inner medullary blood flow decreased 34% at the end of 48 h of water restriction, whereas cortical and outer medullary flow did not change. This fall in inner medullary blood flow was substantially attenuated (18%) by the continuous interstitial infusion of the antagonist. Plasma AVP levels increased from control levels of 3.4 +/- 1.1 to 20.5 +/- 5.4 pg/ml (P < 0.05) by the end of the 48-h period of water restriction. Arterial pressure increased slightly but significantly during water restriction in the control rats. Infusion of antagonist impaired the maximal urinary concentrating ability, as demonstrated by the lower urine osmolality in this group than in the control group (1,893 +/- 49 vs. 2,419 +/- 225 mosmol/kg H2O; P < 0.05) measured during the second day of water restriction. Sodium and urea concentration decreased 20 and 22%, respectively, indicating that both contributed to the lower urine osmolality observed in the group of rats receiving the antagonist. We conclude that water restriction induces a selective decrease in inner medullary blood flow, which is mediated almost completely by endogenously released AVP. This vascular effect of AVP contributes to the maximum concentrating ability of the kidney.

Author List

Franchini KG, Cowley AW Jr

Author

Allen W. Cowley Jr PhD Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Arginine Vasopressin
Hemodynamics
Kidney Concentrating Ability
Kidney Cortex
Kidney Medulla
Laser-Doppler Flowmetry
Male
Rats
Rats, Sprague-Dawley
Renal Circulation
Water Deprivation