AJP - Heart and Circulatory Physiology, Vol 243, Issue 6 896-H902, Copyright © 1982 by American Physiological Society
Ouabain binding and potassium relaxation in aortas from renal hypertensive rabbits
E. C. Hagen, J. C. Johnson and R. C. Webb
This study was designed to characterize the electrogenic sodium pump in
vascular smooth muscle from one-kidney one-clip (1K-1C), renal hypertensive
rabbits. Two measures of the electrogenic pump were used: 1) [3H]ouabain
binding and 2) potassium-induced relaxation. The binding study indicated a
significant increase in the affinity of pump sites for ouabain in aortic
strips from hypertensive rabbits compared with those from normotensive
rabbits (Scatchard analysis). The maximal binding capacity of the binding
sites was similar in the two groups of animals, whereas the concentration
of ouabain at which half-maximal binding occurred was lower in the aortic
strips from hypertensive rabbits. Aortic strips from hypertensive rabbits
showed greater sensitivity to the relaxant effect of potassium after
incubation in potassium-free solution. The potassium-induced relaxation in
aortic strips from hypertensive rabbits was more sensitive to the
inhibitory effect of ouabain than that in strips from normotensive rabbits.
These results suggest that the increased sensitivity to potassium and
ouabain in vascular smooth muscle from hypertensive rabbits is due to an
increased affinity of the pump sites for these substances.
