AJP - Renal Physiology, Vol 249, Issue 1 84-F89, Copyright © 1985 by American Physiological Society
Vasoactive intestinal peptide in the regulation of renin secretion
J. P. Porter, T. N. Thrasher, S. I. Said and W. F. Ganong
We have previously shown that vasoactive intestinal peptide (VIP) is a
renin-stimulating factor both in vivo and in vitro. In the present
investigation we sought to determine whether VIP exerted this effect by a
neural or humoral mechanism. To test for a neural effect, the renal nerves
were stimulated on one side for 30 min in anesthetized dogs, and plasma VIP
and renin levels were determined in the renal venous effluent. The
stimulation significantly increased plasma renin activity in arterial and
renal venous plasma but had no effect on VIP concentrations. A humoral
action was tested in two ways. First, plasma renin activity was measured
before and after elevating circulating levels of endogenously produced VIP
using intravenous neostigmine (0.07 mg/kg) in control, renal-denervated,
and propranolol-pretreated animals. In all three groups, the elevated
plasma level of VIP was associated with a significant increase in plasma
renin activity. Second, plasma levels of VIP were determined in conscious
dogs with elevated plasma renin activity produced by either a low-salt diet
or hemorrhage. In both cases, plasma renin activity was significantly
elevated as expected, but plasma levels of VIP were unchanged. These data
suggest that the effects of VIP on renin secretion are not mediated by
release of the peptide from the renal nerves, the circulating level of
endogenously produced VIP can be elevated sufficiently to stimulate renin
secretion, but a humoral role of VIP in the elevated plasma renin activity
produced by low-salt diet or hemorrhage seems unlikely.+
