Question

Which of the following statements is FALSE of sympathetic activity on ventricular contractile cells?

A) Norepinephrine binds to beta1 adrenergic receptors.
B) Phospholipase C is activated.
C) Calcium channel opening is augmented.
D) The rate of the Ca-ATPase activity is augmented.
E) The rate of the myosin ATPase activity is enhanced.

Answer 1

The rate of the myosin ATPase activity is not enhanced by sympathetic activity on ventricular contractile cells. Hence the correct answer is option E

Step-by-step explanation:

The FALSE statement regarding sympathetic activity on ventricular contractile cells is E) The rate of the myosin ATPase activity is enhanced.

When sympathetic activity is increased, norepinephrine binds to beta1 adrenergic receptors on ventricular contractile cells. This binding leads to the activation of phospholipase C, which in turn increases the opening of calcium channels in the cells. This increased calcium influx enhances the rate of the Ca-ATPase activity, which helps to relax the muscle after contraction. However, the rate of the myosin ATPase activity remains unaffected by sympathetic activity.