Both skeletal muscle and myocardial contraction need calcium ions, but there are triple tubes in skeletal muscle cells, which are rich in calcium ions and independent of extracellular calcium ions. There are only two channels in myocardial cells, and the storage of calcium ions is small, which requires extracellular calcium ions to enter the cells, so myocardial cells rely on extracellular calcium ions.

Calcium channel blockers mainly inhibit extracellular calcium influx by selectively blocking voltage-dependent calcium channels, so calcium channel blockers will not cause skeletal muscle relaxation.

Calcium antagonists, also known as calcium channel blockers, mainly block calcium channels on the cell membrane of myocardial and vascular smooth muscle, inhibit the influx of extracellular calcium ions, reduce the level of intracellular calcium ions, and cause functional changes of cardiovascular and other tissues and organs.

Nifedipine, verapamil and thiazolone are commonly used in clinic. The effect on the heart is mainly to inhibit the influx of the second phase calcium ion in the process of myocardial depolarization, so as to reduce intracellular calcium, myocardial contractility and myocardial oxygen consumption, and at the same time inhibit the influx of calcium in sinoatrial node and atrioventricular node, so as to reduce the autonomy of sinoatrial node, slow atrioventricular conduction and reduce ventricular rate, such as verapamil and azodone.

Please refer to Baidu Encyclopedia-Calcium Antagonists for the above contents.