Cholinergic drug which acts on heart by decrease in levels of cAMP and due to opening of K+ channels is-

Ans. 'a' i.e., Methocholine Characteristics of important subtypes of muscarinic receptor M1M2M31. Location andFunction subservedAutonomicganglia:Gastricglands:CNS:Depolarization (late EPSP)Hist, release, acid secretionLearning, memory motor functionsSA node ; Hyperpolarizatian,| rate of impulse generationAV node: | velocity of conductionAtrium: shortening of APD,| contractilityVentricle: | contractility (slight) (receptors sparse)Cholinergic nerve endings:| ACh release CNS: tremor, analgesiaVisceral smooth mtwc/e:contractionGi/Go-protein coupledK+ channel opening,| cAPMMethacholineMethoctramine, TripitramineVisceral smooth muscle contractionIris : constriction of pupilCiliary muscle: contractionExocrine glands: secretionVascular endothelium: release of NO -2. Nature3. Transducer machanism4. Agonists*5. Antagonists*Gq-protein coupledIP3/DAG - T cytosolic Ca2+PLA2 | PG synthesisACN-343A, OxotremorinePirenzepine, TelenzepineGq-protein coupledIP3/DAG -| cytosolic Ca2+PLA2 | PG synthesis.BethanecholSolifenacin, Darifenacin*Relativelv selectiveACh activates and atropine blocks all 3 subtypes of muscarinic receptors.The CNS contains all subtypes of muscarinic receptors, but Mi appear to predominate.Most smooth muscles and glands have both M2 and M3 subtypes; M3 predominates.