AJP - Renal Physiology, Vol 251, Issue 6 1043-F1048, Copyright © 1986 by American Physiological Society
Renal effects of angiotensin II: modulation by calcium and cyclooxygenase products
B. L. Kasiske, M. P. O'Donnell and W. F. Keane
Modulation of angiotensin II effects on renal function by extracellular
calcium levels and cyclooxygenase products was evaluated using the isolated
perfused rat kidney. Kidneys from normal male Sprague-Dawley rats were
perfused at constant pressure. After base-line assessment of function,
angiotensin II was administered as a bolus and constant infusion; group 1
with normal ionized calcium and 1.2 ng/min angiotensin II, group 2 with
normal ionized calcium and 0.6 ng/min angiotensin II, group 3 with low
ionized calcium and 1.2 ng/min angiotensin II, and group 4 with
indomethacin, low ionized calcium, and 1.2 ng/min angiotensin II.
Angiotensin II caused a marked fall in inulin clearance (CIn) in groups 1
and 2. With low ionized calcium (group 3), angiotensin II increased
resistance to the same degree as in group 2, but in contrast to group 2,
CIn was unchanged. Kidneys perfused with indomethacin (group 4) had marked
angiotensin II-induced declines in CIn that rapidly returned to base line
despite persistently elevated resistance. Thus the results demonstrated
that both calcium and cyclooxygenase products may directly modulate the
effects of angiotensin II on renal function. These effects involve more
than modulation of angiotensin II-induced vasoconstriction.
