Inhibition of positive chronotropic effects of PGE2 by alinidine

Alinidine has been investigated for a possible mode of action in guinea-pig atria. Alinidine up to 10(-6) M did not change the spontaneous rate but inhibited concentration-dependently the positive chronotropic effects of PGE2 in a non-competitive way. The chronotropic effects of adrenaline were not influenced by 10(-6) M alinidine. These results provide evidence for a PGE2 antagonistic action which could be involved in the mechanism of the cardiac slowing effects of alinidine in guinea-pigs.