Cocaine causes vasoconstriction primarily by which mechanism?

Cocaine causes vasoconstriction primarily by which mechanism?

• A. Direct blocking of calcium channels
• B. Potentiating the effect of norepinephrine
• C. Increasing nitric oxide production
• D. Causing vasodilation

Answer: (B)

Cocaine causes vasoconstriction primarily by potentiating the effect of norepinephrine. It does this by blocking the reuptake of norepinephrine at sympathetic nerve terminals, so norepinephrine remains in the synapse longer and more effectively stimulates alpha-adrenergic receptors on vascular smooth muscle, driving constriction. This sympathetic enhancement explains the raised vascular tone and blood pressure seen with cocaine use. The other options don’t fit: direct calcium channel blockade would tend to reduce contraction, increasing nitric oxide promotes dilation, and causing vasodilation is the opposite of what cocaine does.

Cocaine causes vasoconstriction primarily by potentiating the effect of norepinephrine. It does this by blocking the reuptake of norepinephrine at sympathetic nerve terminals, so norepinephrine remains in the synapse longer and more effectively stimulates alpha-adrenergic receptors on vascular smooth muscle, driving constriction. This sympathetic enhancement explains the raised vascular tone and blood pressure seen with cocaine use. The other options don’t fit: direct calcium channel blockade would tend to reduce contraction, increasing nitric oxide promotes dilation, and causing vasodilation is the opposite of what cocaine does.