Epinephrine increases the force of contraction of cardiac muscle by:
A. increasing the amount of Ca++ in the SR for release to the cytosol
B. increasing the level of myosin light-chain phosphorylation
C. inhibiting the ryanodine receptor
D. increasing Ca++ extrusion through the sarcolemmal Ca++ pump
E. shortening the duration of the action potential
ANS: A
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