AJP - Renal Physiology, Vol 252, Issue 2 317-F321, Copyright © 1987 by American Physiological Society
Lack of effect of atriopeptin II on rabbit glomerular arterioles in vitro
R. M. Edwards and E. F. Weidley
This study was designed to determine if atriopeptin II (AP II) has any
direct action on glomerular arterioles in vitro. Single superficial
afferent or efferent arterioles were dissected from rabbit kidney,
cannulated with micropipettes, and changes in lumen diameter were measured.
The effect of AP II (10-(12)-10(-7) M) was tested alone or in arterioles
precontracted with norepinephrine (3 X 10(-7) M, afferent) or angiotensin
II (10(-10) M, efferent). By itself, AP II had no effect on lumen diameter
in afferent or efferent arterioles, but both arterioles responded to 3 X
10(-7) M norepinephrine with 74 and 54% reductions in lumen diameter,
respectively. Similarly, in norepinephrine-contracted afferent arterioles
and angiotensin II-contracted efferent arterioles, AP II did not alter
lumen diameter although acetylcholine (10(-6) M) produced near maximal
relaxation of both arterioles. Furthermore, luminal addition of AP II
(10(-7) M) had no effect on control lumen diameter or on the response to
norepinephrine or angiotensin II. The preparation of AP II was biologically
active since it caused dose-dependent increases in guanosine 3',5'-cyclic
monophosphate levels in isolated rat glomeruli. These results suggest that
the renal vascular effects of AP II observed in vivo are not due to a
direct action on superficial glomerular arterioles but rather to an, as
yet, unidentified indirect action of this peptide.
