AJP - Renal Physiology, Vol 250, Issue 1 109-F114, Copyright © 1986 by American Physiological Society
Effects of ouabain on autoregulation of renal blood flow in dogs
T. Tamaki, K. Fukui, S. Fujioka, H. Iwao, T. Okahara and Y. Abe
Effects of ouabain on the autoregulation of renal blood flow (RBF) and
renin release were examined in filtering and nonfiltering kidneys of
anesthetized dogs. Autoregulation of RBF was observed in both kidneys;
however, autoregulation in the nonfiltering kidney was comparatively less
efficient. These findings indicate that both the myogenic mechanism via a
sensor element in the afferent arteriole, a so-called baroreceptor, and the
tubuloglomerular feedback mechanism via the macula densa are essential for
complete autoregulation. In both the control and nonfiltering kidney,
intrarenal arterial infusion of ouabain abolished the autoregulation of RBF
and glomerular filtration rate, with no change in the renal vascular
sensitivity to vasoactive substances or in renin release induced by
pressure reduction. Since various vasoactive drugs elicited a normal
vascular response, it appears that the site of action of ouabain was not
the vascular contractile elements; at least, an impairment of
autoregulation during ouabain infusion was apparently not due to a defect
in these elements. These results suggest the possible existence of another
mediator, a sensor element in the afferent arteriole that is affected by
ouabain. Ouabain may abolish the autoregulation of RBF and renin release
via a modification of this baroreceptor in the afferent arteriole as well
as through inhibition of the macula densa.
