The effects of 9, 11-epihio-11, 12-methano-thromboxane A2 (STA2), a stable analogue to thromboxane A2, on platelet aggregation and its interaction with α blockers (phentolamine, prazosin and yohimbine) were studied in both mongrel dogs and healthy male volunteers in vitro.
The results were as follows; (1) In dogs, though STA2 did not have a potency of inducing platelet aggregation, STA2 revealed enhancing effect on platelet aggregation induced by epinephrine, and this effect of STA2 was inhibited by α blockers, especially α2 blockers, (2) In healthy volunteers, STA2 itself induced platelet aggregation, and this effect of STA2 was also inhibited by α blockers, but dominancy of α1 or α2 blocker was unclear.
It was concluded from these data that STA2 was a potent platelet aggregatory agent in human and this activity was inhibited by α blockers.
