Activation of which of the following receptor cause vasoconstriction?

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