Thank you for the opportunity to help you with your question!
The calcium-channel blockers represent a group of organic chemical
structures that share the ability to inhibit Ca2+ entry into excitable
cells. In cardiac contractile cells,
inhibition of Ca2+ entry blunts the ability of Ca2+ to serve as an
intracellular messenger. Thus, calcium-channel blockers have a negative inotropic effect on the
working myocardial cells of the atria and ventricles. Calcium-channel
blockers also have effects on impulse formation and conduction in some
regions of the heart.
Please let me know in case of any clarification. I'm always available to answer your questions.