What is the effect of the parasympathetic nervous system on the heart rate?

When a normal man's heart is injected with a physiological concentration of adrenaline,it causes:

Neural signals through ............ can increase the rate of heart beat,the strength of ventricular contraction and thereby the cardiac output.

What happens to the heart rate if the parasympathetic nerve of a rabbit is cut?

$A$: The resting heart rate,about $75$ beats/minute,is usually lower than the autorhythmic rate of the $SA$ node ($90-100$ beats/minute).
$R$: At rest,the parasympathetic nervous system effects dominate the heart rate.

Heart is innervated by