Cocaine vasoconstriction mechanism

Cocaine vasoconstriction mechanism

• A. Potentiates norepinephrine
• B. Inhibits reuptake of norepinephrine
• C. Blocks dopamine reuptake
• D. Activates endothelin release

Answer: (A)

Cocaine causes vasoconstriction mainly by boosting norepinephrine signaling in the sympathetic nervous system. It blocks the norepinephrine transporter (NET) on presynaptic nerve endings, so norepinephrine stays in the synaptic cleft longer and at higher levels. That increased norepinephrine activity strongly stimulates alpha-adrenergic receptors on vascular smooth muscle, especially alpha-1 receptors, leading to contraction of the vessels and vasoconstriction. So describing the effect as potentiating norepinephrine captures the net result: heightened norepinephrine action drives the vascular tighten­ing. Cocaine does also affect dopamine and serotonin reuptake, but the vasoconstrictive effect is best explained by the enhanced norepinephrine signaling. Endothelin release isn’t the primary mechanism here.

Cocaine causes vasoconstriction mainly by boosting norepinephrine signaling in the sympathetic nervous system. It blocks the norepinephrine transporter (NET) on presynaptic nerve endings, so norepinephrine stays in the synaptic cleft longer and at higher levels. That increased norepinephrine activity strongly stimulates alpha-adrenergic receptors on vascular smooth muscle, especially alpha-1 receptors, leading to contraction of the vessels and vasoconstriction. So describing the effect as potentiating norepinephrine captures the net result: heightened norepinephrine action drives the vascular tighten­ing.

Cocaine does also affect dopamine and serotonin reuptake, but the vasoconstrictive effect is best explained by the enhanced norepinephrine signaling. Endothelin release isn’t the primary mechanism here.