Nicardipine dose dependently reduces the effect of equinatoxin II on coronary flow in isolated rat heart

Equinatoxin Il (EqT II) decreases coronary flow in guinea-pig and rat heart . It increases cytosolic Ca2+ activity and is supposed to form cation selec tive membrane pores. In the present study we tried to evaluate the influenc e of the L-type Ca2+ channel antagonist nicardipine upon the vasoconstricto ry effect of EqT II on coronary vessels in isolated heart of the rat. Coron ary flow was measured during the experiment. Ten min after bolus injection of EqT II the coronary flow decreased to 17.2 +/- 4.3% in experiments witho ut nicardipine, and to 39.4 +/- 4.5% in the group with 0.1 muM nicardipine (p <0.05). Our results indicate the possibility that L-type Ca2+ channels c ould be involved in the effects of EqT II on coronary flow in the rat heart .