title: The adenylate cyclase activity in heart membranes from normotensive and spontaneously hypertensive rats, after chemical sympathectomy, suggests the presence of presynaptic secretin receptors.
abstract: Normotensive (WKY) and spontaneously hypertensive (SHR) male adult rats were sacrificed 2 and 3 weeks after 6-hydroxydopamine treatment. Untreated WKY and SHR rats served as controls. In rat heart membranes from WKY rats, 6-hydroxydopamine treatment increased guanosine 5'-O-(2-3-imido)-triphosphate (Gpp(NH)p)-, NaF-, D,L-isoproterenol- and glucagon-stimulated adenylate cyclase activities by 18-38% while secretin stimulation was unaffected. In heart membranes from SHR rats, Gpp(NH)p, NaF, D,L-isoproterenol, or glucagon stimulation of the enzyme was similarly increased by 14-38% whilst the low secretin responsiveness which is characteristic of these animals decreased even further (by 24-47%). These results are consistent with: (1) an up regulation of postsynaptic beta-adrenergic receptors coupled to adenylate cyclase after degeneration of adrenergic nerves, and (2) a differential response of secretin receptors coupled to adenylate cyclase in the two strains of rats: there was no change in WKY rats and a decreased response in SHR rats. The possible presence and contribution of presynaptic secretin cardiac receptors is considered.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006892:Hydroxydopamines / Q000494:pharmacology; D006973:Hypertension / Q000201:enzymology*; D008297:Male; D008566:Membranes / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology*; D009929:Organ Size / Q000187:drug effects; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; D013563:Sympathectomy, Chemical; D013997:Time Factors
chemical_list: D006892:Hydroxydopamines; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; C029937:secretin receptor; D016627:Oxidopamine; D000262:Adenylyl Cyclases