Comparison of the actions of 11.9 epoxymethano PGH2 and 9.11 azo PGH2 on rat aorta and stomach strip preparations.

Two synthetic thromboxane A2 agonists were compared on two isolated smooth muscle preparations, the rat aorta and stomach-strip using a superfusion cascade. 11.9 epoxymethano-PGH2 contracted both preparations in a concentration dependent manner. Cumulative concentration-response curves showed that azo PGH2 was twice as active as 11.9 epoxymethano PGH2 on the aorta and nearly four times Statistical analysis of the agonist concentration-response curves showed a significant difference when responses to azo PGH2 were compared on the two preparations and when responses to azo PGH2 and 11.9 epoxymethano PGH2 were compared on the aorta preparation. When EPO45, a thromboxane receptor antagonist was used the PA2 values obtained were not significantly different using the two agonists on the two preparations. The pA2 values indicate that both agonists act on the same receptor but the comparison of the concentration-response curves suggest that azo PGH2 may be acting at another receptor as well as the thromboxane receptor in the stomach-strip.