Effects of levocarnitine chloride (LC-80) on hemodynamics and myocardial metabolism in anesthetized open-chest dogs under normoxic or hypoxic conditions

Abstract

The effects of LC-80, infused intravenously at a rate of 10 mg/kg/min for 30 min, on hemodynamics and myocardial metabolism were investigated in anesthetized open-chest dog preparations under a normal oxygen tension of arterial blood (PaO2) ranging from 100 to 120 mmHg or low PaO2 ranging from 40 to 50 mmHg. (1) Normal PaO2 + High free fatty acidemia (HFFA): HFFA was produced by the intravenous infusion of Intralipid at a rate of 0.1 ml/kg/min after the rapid intravenous injection of 500 U/kg of heparin. Under this experimental condition, no significant changes in hemodynamics and myocardial metabolism were observed in both the LC-80 treated group and control group. (2) Low PaO2 + HFFA: Under this condition, there was no significant difference in hemodynamics between the LC-80 treated group and the control group, and the myocardial function in both groups tended to decrease. However, the increase in the coronary flow of the LC-80 treated group tended to be slight as compared with that of the control group. On the other hand, the decrease in the arterio-coronary venous difference of lactate was significantly less in the LC-80 treated group as compared to that in the control group. Furthermore, the reduction in myocardial redox potential (delta Eh) of the LC-80 treated group tended to be slight as compared with that of the control group. (3) Low PaO2 + HFFA + stress load: The hemodynamic responses (heart rate, left ventricular pressure, max dP/dt and cardiac work) to isoproterenol-induced stress were slightly but not significantly better in the LC-80 treated group than in the control group. While myocardial lactate production and the reduction of delta Eh in both groups became more prominent under this experimental condition, their degrees were apparently less in the LC-80 treated group as compared to those in the control group. These results suggest that LC-80 may have an improving effect on the anaerobic myocardial metabolism under anaerobic conditions such as hypoxia or stress load.