Case Discussion
Answer the case with reason
A 55-year-old man presents for follow-up regarding his hypertension and coronary artery disease. Despite multiple medications, his blood pressure remains poorly controlled. His physician is considering adding verapamil to his treatment regimen. Verapamil is a vasodilator that can help manage systemic hypertension and also reduces cardiac contractility. However, it has minimal effects on skeletal muscle. Which of the following characteristics of skeletal muscle explains its relative resistance to verapamil?
A. Excitation-contraction coupling that is independent of calomodulin
B. Reduced troponin sensitivity to intracellular calcium
C. Highly developed transverse (T)-tubule system
D. Absence of intrinsic automaticity
E. Minimal reliance on extracellular calcium influx