Coronary blood flow to the left ventricle increases during

A. False  It falls; coronary vessels are compressed by the contracting myocardium.

B. True  A fall in PO2 has a potent vasodilator effect on coronary vessels. Adenosine released from hypoxic myocardium is also a potent vasodilator.

C. False  The fall in metabolic rate and cardiac output in hypothermia reduce cardiac work and lead to a reduction in coronary blood flow.

D. True  Sympathetic stimulation increases the rate and force of contraction; the resulting increase in the rate of production of vasodilator metabolites dilates coronary vessels.

E. True  Myocardial work and metabolism are increased in hypertension.