Effect of norepinephrine on myocardial intracellular hydrogen ion concentration.
The effect of norepinephrine (NE) on the intracellular hydrogen ion concentration [H+]i of isolated rat hearts perfused with a modified Krebs-Henseleit solution (SHS) was determined. The [H+]i was calculated with the [14C]-dimethyloxazolidinedione method. Respiratory or metabolic acidosis was produced by equilibrating the KHS with 20% C02 or decreasing the [HC03-] of the KHS, respectively. Three types of experiments were carried out: 1) beta blockade--MJ 1999 (Sotalol) was added to the KHS; 2) control--no pharmacological treatment; and 3) NE-norepinephrine was added to the KHS. The effective CO2 buffer values (delta[HC03-]i/deltapHi) during respiratory acidosis were: beta blockade, 11; control, 35; and NE, 84. The production of metabolic acidosis resulted in the following [H+]i changes: beta blockade, 52 mM; control, 60 nM; and NE 7 nM. These results suggest that NE markedly attenuates the changes in [H+]i accompanying respiratory and metabolic acidosis and may account in part for previous observations that the effective C02 buffer value of cardiac muscle in vivo is greater than that in vitro.
D000137:Acid-Base Imbalance / Q000378:metabolism; D000138:Acidosis / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption; D051381:Rats; D013015:Sotalol / Q000494:pharmacology
D001639:Bicarbonates; D002245:Carbon Dioxide; D013015:Sotalol; D009638:Norepinephrine