Effect of verapamil on contractility, oxygen utilization, and calcium exchangeability in mammalian heart muscle

Abstract

The negative inotropic effect of verapamil is accompanied by a reduction in the myocardial demand for O₂ and an improved efficiency. This negative inotropic effect is due neither to sympathetic blockade nor to an altered ability of the sarcoplasmic reticulum to accumulate, bind, or exchange Ca²⁺ . The capacity of membrane-located binding sites to accumulate Ca²⁺ is, however, impaired.