Influences of low sodium diets on vascular effects of bradykinin and on bradykinin receptors in the uterine smooth muscle in the rats.

A low sodium diet for 7 days in the rat induced an enhancement of the vascular effects of bradykinin, determined as the blood pressure response, by 56%. However, this enhancement reverted after 28 days of a low sodium diet. A sustained increase in the number of uterine smooth muscle bradykinin receptors during low sodium diets was observed, 1.3 times of the control on the 7th day and 1.7 times on the 28th day. No change in binding affinity was found in any of the studies. These results suggest that the vascular effects of bradykinin after low sodium diets may be regulated by homeostatic mechanisms via the change in the number of vascular smooth muscle bradykinin receptors at subcellular levels, and that the number of uterine smooth muscle bradykinin receptors may be affected by sodium status per se.