Blood pressure changes in spontaneously hypertensive rats correlate with aortic prostacyclin formation.

1 The relationship between the blood pressure fall, induced by antihypertensive drugs or bleeding, and the formation of prostacyclin (PGI2)-like activity in the thoracic aorta of spontaneously hypertensive rats has been investigated. Inhibition of ADP-induced platelet aggregation was used to assess PGI2-like activity. 2 The decreases in blood pressure produced by clonidine, dihydralazine and prazosin were associated with increases of PGI2-like activity of 50-80%. The increase in PGI2-like activity correlated well with the blood pressure decrease, independently of the mechanism of the fall in blood pressure.