Catecholamine effect on HCO3-/Cl- exchange and rabbit myocardial cell pH regulation.
The possible effect of isoproterenol on a HCO3-/Cl- exchange in mammalian myocardium and its role on intracellular pH (pHi) regulation was studied in isolated perfused rabbit hearts. pHi was determined from the distribution of 5.5-dimethyl-2,4-oxazolidinedione (DMO). Perfusates contained either 137.4 or 4.4 mM Cl-. In the latter case, Cl- was replaced by glucuronate. Hearts were perfused with low [Cl-] Ringer for 1 h in order to deplete the cell of Cl-. Isoproterenol (10(-5) M) was infused for the last 15 min of perfusion in approximately half of the preparations. Reduction of [Cl-], both in the untreated and in the isoproterenol-treated preparations resulted in an increase in pHi. Isoproterenol increased tissue cAMP concentration by approximately 2.5 fold both in hearts perfused with normal and with low [Cl-] Ringer. In the presence of normal [Cl-], isoproterenol had an alkalinizing effect when acid loads were introduced. This effect was abolished by the reduction of [Cl-]. These results support the idea that the catecholamine-cAMP system stimulates a HCO3-/Cl- exchange in mammalian myocardium.
D000136:Acid-Base Equilibrium / Q000187:drug effects*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood; D002712:Chlorides / Q000378:metabolism*; D003326:Coronary Circulation / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010477:Perfusion; D011817:Rabbits; D014655:Vascular Resistance / Q000187:drug effects
D001639:Bicarbonates; D002712:Chlorides; D002245:Carbon Dioxide; D000242:Cyclic AMP; D007545:Isoproterenol