The dose-response curves obtained in the measurement of the prostaglandin E (PGE) and thromboxane-A2 (TxA2)-like activity using a cascade system cons isting of a rat stomach strip , a rabbit aorta strip and a mesenteric artery were determined. The following linear relat ionships were observed:log dose-activity for PGE2 and the stomach strip , do se-activity for angiotensin II (All) and the rabbit aorta, log dose-log activity for angiotensin II and the rabbit mesenteric artery.The do se-activity curves for All and TxA2 are different when the rabbit aorta is used whereas the log dose-log activity curves are much more similar for the rabbit mesenteric artery. Therefore, AI I can only be used as a reference substance in the last case. A comparison was made of the TxA2 like activity measured by bioassay and the TxB2 determined by a radioimmunoassay in platelets after aggregation. The curves were parallel when the TxA2 like activity was measured with the mesenteric artery.The different contractile characteristics of these organs should be taken into account in the determination of the PGE2 like and TxA2 like activity with these tests.
Angiotensin II activates two cation conductances with distinct TRPC1 and TRPC6 channel properties in rabbit mesenteric artery myocytes