A pharmacist is studying the mechanism of action of verapamil on the muscle tissue in the pathients who have a hypertension. He found that verapamil affects cardiac contractility but has a minimal effect on skeletal muscle. Which of the following properties of skeletal muscle is responsible for its resistance to the medication?

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Quizplus · Accepted Answer

Eductional Objective: Contraction initiation in cardiac and smooth muscle cells is dependent on extracellular calcium influx through L-type calcium channels, which can be prevented by calcium channel blockers (eg, verapamil). Skeletal muscle is resistant to calcium channel blockers, as calcium release by the sarcoplasmic reticulum is triggered by a mechanical interaction between L-type and RyR calcium channels.

A Pharmacist Is Studying the Mechanism of Action of Verapamil