ACUTE AND CHRONIC EFFECTS OF ANTI-ENDOTHELIN-1 ANTIBODY ON BLOOD-PRESSURE IN SPONTANEOUSLY HYPERTENSIVE RATS

To evaluate the significance of endogenous endothelin (ET) in the maintenance of blood pressure in hypertensive and normotensive conditions, we examined the acute and chronic effects of anti-ET-1 antibody in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats. Immunoglobulin (Ig) solution purified from anti-ET-1 rabbit serum was injected intravenously in conscious rats aged 12-14 weeks (SHR: n = 7, WKY: n = 7). In the control group (SHR: n = 5, WKY: n = 4), Ig prepared from nonimmune rabbit serum was administered. One week after the first injections of Ig, second intravenous injections were given. After the intravenous injections of ET-1 antibody, there were no significant changes in directly measured blood pressure (BP) for up to 60 min in both strains. On the first, third, and seventh days after the first administration of ET-1 antibody, as well as on the first, third, and seventh days after the second injection, there were no appreciable differences in BP between SHR treated with anti-ET-1 antibody and SHR with control Ig. No significant changes in BP were observed throughout the observation period in WKY groups. Plasma levels of immunoreactive ET-1 were similar in SHR and WKY. This study suggests that circulating ET may not play a significant role in the maintenance of hypertension in SHRs or in the regulation of blood pressure in WKY rats.