The Inotropic Effect of Sym Pathetic Stim Ulation is Due

Question

The inotropic effect of sym pathetic stim ulation is due mainly to A) Decreased duration of the action potential B) Increased size of the Ca²⁺ transient C) Increased affinity of TnC for Ca²⁺ D) Increased rate of relaxation E) Increased amplitude of the action potential

Accepted Answer

The inotropic effect of sympathetic stimulation is primarily due to an increased size of the calcium transient. This is because sympathetic stimulation leads to the release of norepinephrine, which activates beta-adrenergic receptors on the heart muscle cells, leading to increased cyclic AMP and subsequently enhanced calcium influx during the action potential. This increased calcium availability is what boosts the contractility (inotropic effect) of the heart.