Effect of cocaine on blood vessels is?
**Core Concept**
Cocaine is a potent vasoconstrictor that affects blood vessels by inhibiting the reuptake of norepinephrine, a neurotransmitter that causes blood vessels to constrict. This leads to an increase in peripheral resistance and a subsequent increase in blood pressure.
**Why the Correct Answer is Right**
Cocaine's vasoconstrictive effects are primarily mediated through its action on the sympathetic nervous system, specifically the release of norepinephrine from the terminals of postganglionic sympathetic neurons. Norepinephrine then binds to alpha-adrenergic receptors on the smooth muscle cells of blood vessels, causing vasoconstriction. This results in a decrease in blood flow to the skin and other peripheral tissues, leading to a characteristic "cocaine-induced" vasoconstriction.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because cocaine's primary effect on blood vessels is not vasodilation.
**Option B:** Incorrect because cocaine's vasoconstrictive effects are not primarily mediated through the release of histamine.
**Option C:** Incorrect because cocaine's vasoconstrictive effects are not primarily mediated through the release of acetylcholine.
**Clinical Pearl / High-Yield Fact**
Cocaine can cause severe vasoconstriction and subsequent ischemia, particularly in the coronary and cerebral circulations, leading to myocardial infarction and stroke, respectively.
**Correct Answer:** C. Cocaine causes vasoconstriction.