[Action of a sodium lactate perfusion on the hemodynamic effects of beta-blockaders]

In 15 dogs who had been given propranolol and 5 humans who had been given Pindolol, an infusion of sodium lactate produced: 1) an increased in blood lactate levels and pH; 2) an increase in the cardiac index; 3) a state in which an infusion of isoproterenol (inactive on its own) could act as it would have done had the betaadrenergic receptors not been blocked. A perfusion of lactic acid which was sufficient to cause the variations in pH and blood lactate levels that are seen with exercise had no action on the heart rate nor on the cardiac index of 10 dogs treated with propranolol and could not re-establish the betastimulating properties of isoproterenol. Finally, alkalosis produced by an infusion of THAM in 13 dogs or sodium bicarbonate in 2 humans, changed neither the cardiac index nor the heart rate, nor the response to isoproterenol after a betaadrenergic blockade. Infusion of sodium lactate associated with isoproterenol could be used to combat the depressent effects of betablockers in patients with cardiac disorders.