Mechanism of the increased cardiac Ca2+ uptake induced by isoprenaline in DOCA-salt pretreated rats.
Desoxycorticosterone acetate (DOCA)-salt supersensitivity to isoprenaline (isoproterenol) was demonstrated by the increase in cardiac Na+ and Ca2+ content and by the decrease in cardiac Mg2+ content that occurs at lower isoprenaline doses in DOCA-salt pretreated rats compared to control rats. The number of beta-adrenoceptors in the myocardium as measured by [3H]-dihydroalprenolol binding amounted to 170 +/- 18 fmol/mg protein in normal rats and to 150 +/- 17 fmol/mg protein in DOCA-salt pretreated rats. The dissociation constant amounted to 2.6 +/- 0.4 nmol/l for normal and to 2.8 +/- 0.5 nmol/l for pretreated rats. The isoprenaline-induced increased cardiac Ca2+ content in DOCA-salt pretreated rats can be explained by the increased adenylate cyclase activity and by the resulting increased Ca2+ influx via phosphorylated calciductin.
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D003900:Desoxycorticosterone / Q000494:pharmacology*; D004573:Electrolytes / Q000097:blood; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*
D004573:Electrolytes; D011943:Receptors, Adrenergic, beta; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D002118:Calcium