Endothelin and blood pressure in pregnant, spontaneously hypertensive rats

The study was conducted to determine whether endothelin (ET)receptor antago nism affects blood pressure in spontaneously hypertensive rats (SHRs) durin g pregnancy. Sixteen pregnant rats were given bosentan (Ro 47-0203/029), a nonspecific ETA/ETB antagonist, at a dose of 100 mg/kg of body weight. Four teen untreated pregnant rats served as controls. Body weight, systolic bloo d pressure, and plasma ET levels mere measured 3 times during the pregnancy and once 3 to 5 days after delivery. Blood pressure was measured using the indirect tail-cuff method with an electrosphygmomanometer and a pneumatic pulse transducer. The expected decrease in blood pressure during pregnancy occurred in both the bosentan-treated and the untreated animals. The plasma ET level in the bosentan-treated group increased 8 days after starting tre atment and decreased after delivery. The plasma ET level remained unchanged in the untreated animals until after delivery, when it increased. ET does not appear to play a significant role in the maintenance of blood pressure in pregnant SHRs.