Characterization of renin activity in brown adipose tissue.
Shenoy, Ujjwala, and Lisa Cassis.
Division of Pharmacology and Experimental Therapeutics, College of
Pharmacy, University of Kentucky, Rose Street, Lexington, Kentucky,
40508
APStracts 3:0316C, 1996.
Angiotensin II (AII) plays a vital role in blood pressure regulation
and body fluid homeostasis. Although many peripheral tissues
synthesize components of the renin-angiotensin system, very few
synthesize all of the major components involved in the generation of
AII. This study used interscapular brown adipose tissue (ISBAT) as a
model system to evaluate the mechanism of AII generation in an
extrarenal tissue. Polymerase chain reaction analysis of DNA from
ISBAT demonstrated angiotensinogen gene expression; however, renin
gene expression was not detected. Renin activity was detected in
ISBAT homogenates which was not completely derived from the residual
blood pool. Kinetic parameters for renin activity were similar in
ISBAT and adrenal. Renin activity was partially inhibited by anti
-renin antibody and completely inhibited by a specific rat renin
inhibitor. Bilateral nephrectomy did not decrease renin activity in
ISBAT. Western blot analysis, employing two species-specific renin
antibodies, indicated the presence of a variety of isoforms of renin
in ISBAT. The presence of renin activity in isolated brown adipocytes
demonstrated the enzyme is localized to adipocytes. The release of
immunoreactive angiotensin peptides from ISBAT slices over 3 hours
indicated de-novo synthesis. These studies support the existence of a
local renin-angiotensin system in ISBAT and suggest involvement of
renin in the formation of AII.
Received 29 March 1996; accepted in final form 26 September 1996.
APS Manuscript Number C179-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996