[The calcium-antagonistic fundamental effects of Verapamil on myocardial fibers and smooth muscle cells of the blood vessels].

Ca ions regulate the amount of ATP which is metabolized in the contractile system to produce mechanical energy. Since the consumption of ATP quantitatively determines the myocardial respiration rate, oxygen consumption is also Ca-dependent. Therefore, Ca-antagonistic compounds such as verapamil, D600 or nifedipine, by reducing the Ca supply to the beating heart, not only restrict ATP breakdown and mechanical activity but also myocardial oxygen demand. Moreover, Ca-antagonistic drugs lower the tone of vascular smooth muscle. This action leads to coronary vasodilation and a reduction in heart load because the peripheral vascular resistance is also diminished. All these factors contribute to an improvement of the cardiac energy balance in patients with coronary disease.