Calcium entry blockers and receptor-response coupling.

This review summarizes experiments investigating how Ca entry blockers interfere with receptor-response coupling in vascular tissue. It is shown that stimulatory agents increase smooth muscle membrane permeability to Ca by opening specific channels. The action of Ca entry blockers (namely, cinnarizine, diltiazem, flunarizine, and nifedipine) may be attributed to a specific blockade of these channels, as shown by a superimposition of dose-inhibition curves of contraction and Ca entry. Among the main characteristics of such drugs are their receptor and tissue selectivity. This is the basis for understanding that drugs having a common mechanism (Ca channel blockade) may present different pharmacological profiles and have different therapeutic indications.