This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'Activation of which of the following receptor cause vasoconstriction? \nSelect and explain. \nA. Nm receptor, B. M3 receptor, C. Nn receptor, D. ETa receptor', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans: d (ETa receptor) Ref: Ganong, 22nd ed, p. 600ET receptors:ETa - specific for endothelin 1 - G coupled- vasoconstrictionETb- Responds to all 3 endothelins - G1 coupled - vasodilatationM3 receptors cause vasodilatation by release of NO & visceral smooth muscle contraction.Nm - They are present in skeletal muscle & cause constriction but not vasoconstriction.Na - They are present on ganglionic cells not on vascular smooth muscle. M,m2m3SITEAutonomic ganglia,Gastric glandsCVSVisceral smooth muscleExocrine glandsVascular endothelium (vasodilator)AGONISTOxotremorineMethacholineBethanecholANTAGONISTPirenzepine,TelenzepineMethoctramineTripitamineHexahydrosiladifendiolDarifenacin (All India) NmNnSITESkeletal muscleAutonomic gangliaAdrenal medullaAGONISTPTMANicotineDMPPNicotineANTAGONISTTubocurarinea bungarotoxinHexamethoniumTrimethophan', 'role': 'assistant'}]