Which of the following is associated with decrease in cardiac output?

The sympathetic nerve ending releases noradrenaline which stimulates the SAN that accelerates the heartbeat, the strength of ventricular contraction and thereby the cardiac output.

The parasympathetic nerve ending releases acetylcholine which decreases the rate of heartbeat, speed of conduction of action potential and thereby the cardiac output.

The adrenal medulla of the adrenal gland secretes two hormones called adrenaline and noradrenaline. Both the hormones are rapidly secreted in response to the stress of any kind and during emergency situations. These hormones increase the heartbeat and strength of heart contraction. Thus, adrenal medullary hormones can also increase cardiac output.

The pneumotaxic centre increases the rate of pulmonary ventilation, which in turn increases heartbeat and thus cardiac output.