AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 6 1250-R1257, Copyright © 1989 by American Physiological Society
Glomerular and vascular atrial natriuretic factor receptors in adrenalectomized rats
V. Cachofeiro, E. L. Schiffrin, M. Cantin and R. Garcia
Laboratory of Experimental Hypertension and Vasoactive Peptides, Clinical Research Institute of Montreal, Quebec, Canada.
The renal and vascular responses to atrial natriuretic factor (ANF) and
glomerular and vascular ANF receptors were studied in adrenalectomized
(ADR) rats with or without deoxycorticosterone (DOC) or dexamethasone
(Dexa) replacement therapy. As expected, adrenalectomy elicited
hypotension, hemoconcentration, and increased plasma renin activity, but no
changes in plasma levels of either ANF-(1-98) or ANF-(99-126) were
detected. Dexa treatment decreased both ANF-(1-98) and ANF-(99-126),
whereas DOC treatment increased only ANF-(1-98). The acute renal response
to ANF and furosemide was reduced in ADR rats and partially restored either
by steroid replacement or by raising blood pressure. The blunted
natriuretic response to ANF in ADR rats was associated with an increased
density of glomerular receptors. Norepinephrine-precontracted vascular
strips from ADR rats were more sensitive to ANF (ED50: 1.7 x 10(-8) M) than
those from sham-operated animals (ED50: 1.5 x 10(-7) M). However, vascular
ANF receptor density in mesenteric vessels from ADR animals was decreased.
Dexa treatment restored vascular response to that observed in sham-operated
animals without a concomitant change in vascular receptor density. Because
the presence of guanylate cyclase-coupled and noncoupled ANF receptor
subtypes have been described in different tissues, we conclude that the
apparent lack of correlation between the biological response to ANF and
total binding of ANF to glomeruli or mesenteric artery membranes in ADR
rats may be in part caused by a differential regulation of both receptor
subtype populations.
