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Vasopressin V1a Vasopressor — FRCA Primary MCQ

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ModeratePharmacology - CardiovascularVasopressin V1a VasopressorFRCA Primary

Vasopressin (ADH) used as a vasopressor in septic shock acts via which receptor?

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Correct answer: B — V1a receptors on vascular smooth muscle

In septic shock vasopressin acts on V1a receptors on vascular smooth muscle causing vasoconstriction. This is distinct from its V2 receptor-mediated antidiuretic effect on the renal collecting duct. Vasopressin levels are inappropriately low in late septic shock providing a rationale for its use as a vasopressor.

Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care