Increased cAMP as a downstream event of epinephrine and norepinephrine stimulation of the left ventricle produce PKA. Which of the following events in the cardiac muscle physiology is influenced by the increase in PKA?

A. Action potential enters from
B. Voltage-gated Ca2+ channels
C. Ca2+ induces Ca2+ release adjacent cell open. Ca2+ enters the cell through ryanodine receptor channels (RyR2)
D. Local release causes Ca2+ spark.
E. Ca2+ ions bind to troponin to initiate contraction
F. Relaxation occurs when Ca2+ unbinds from troponin
G. Ca2+ is pumped back into the sarcoplasmic reticulum for storage
H. Ca2+ is exchanged with Na+
I. Na+ gradient is maintained by the Na+/K+ ATPase

Modulation of Ca+2 channel Epinephrine also causes an increase in cAMP that stimulates PKA that is protein kinase A, which in turn phosphorylates the voltage-gated Ca+2 channel that is the L channel. This phosphorylation results in a protein conformational change that enchances the channels activity.

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