Which statement is true regarding chlorpromazine's effect on CPB vascular tone?

• A. It vasoconstricts
• B. No effect on vascular tone
• C. Increases heart rate
• D. It vasodilates

Answer: (D)

Chlorpromazine lowers vascular tone by blocking alpha-1 adrenergic receptors on vascular smooth muscle. This prevents norepinephrine from causing constriction, so the vessels relax and dilate. In the CPB setting, that means a decrease in systemic vascular resistance and vasodilation rather than constriction. While heart rate might rise reflexively to help maintain blood pressure, the direct impact on vascular tone is vasodilation.