Influence of Bradykinin on Blood Pressure Regulation of Spontaneously Hypertensive Rats Maintained on Different Sodium Intakes

1. The role of circulating bradykinin in blood pressure regulation was studied in conscious spontaneously hypertensive rats utilizing the competitive antagonist of bradykinin B4162. 2. This antagonist was administered at a bolus dose (400 micrograms i.v.) known to block the hypotensive effect of exogenous bradykinin for at least 2 min. The rats were maintained for 10 days either on a low or a high sodium intake. 3. The antagonist of bradykinin significantly increased blood pressure only in salt-depleted rats. In other rats kept on a low or a high sodium intake, dose-response curves to exogenous bradykinin were established. Dietary sodium had no influence on the blood pressure-lowering effect of bradykinin. 4. These data therefore suggest that circulating bradykinin may be involved in the blood pressure control of spontaneously hypertensive rats when the renin-angiotensin system is stimulated by salt depletion.