Contrasting Effect of Thromboxane Synthase Inhibitors and a Thromboxane Receptor Antagonist on the Development of

This study was designed to contrast the effects of prolonged treatment with a thromboxane (Tx) synthase inhibitor (UK 38485 or SC 41 156) and a Tx receptor antagonist (SQ 29548) on the development of angiotensin II (Ang 11)-salt-induced hypertension. Ang II infusion (1 25 ng/min i.p. for 1 2 days) in rats drinking 0.15 M NaCI resulted in severe hypertension accompanied by protein-una, reduction of urinary creatinine excretion and augmentation of urinary TxB2 excretion and TxB2 release from aortic rings and renal cortex slices. In saline-drinking rats undergoing Ang II infusion, the concomitant administration by gavage of UK 38485 (1 00 mg/kg/day) or SC 41 1 56 (25 mg/kg/day) reduced serum and urinary TxB2 and TxB2 release from aortic rings and/or renal cortex slices, but it was without effect on the development of hypertension. In contrast, concomitant infusion of SQ 29548(4.