THE RELATIONSHIP BETWEEN ENDOTHELIN AND BLOOD-PRESSURE IN PREGNANT RATS

Objective: The role of endothelin in the maintenance and regulation of hypertension in spontaneously hypertensive and Wistar Kyoto rats is c ontroversial. In view of the meager data on pregnant rats, endothelin levels and blood pressure were examined before and during pregnancy in these two strains of rats. Methods: Endothelin levels were determined with a I-125 ET radioimmunoassay (RIA) kit. Systolic blood pressure w as measured in conscious animals by an indirect tail cuff method using an electrosphygmomanometer and pneumatic pulse transducer (Narco Bios ystems, Inc., Houston, TX). The mean of 3 measurements was recorded as a representative blood pressure for each rat. Results: The decrease i n blood pressure in the spontaneously hypertensive rats (SHR) during p regnancy was very impressive, and the endothelin level also fell signi ficantly. There was no change in endothelin level in Wistar Kyoto rats (WKY) and the fall in blood pressure was also less pronounced. Conclu sions: These data indicate a mutual relationship between blood pressur e and endothelin level.