Background
Oxygen-derived free radicals are involved in tissue damage during myocardial ischemia and reperfusion. Recent in vitro studies have demonstrated that a beneficial effect of propofol lies on its free radical scavenging properties. The current study, therefore, examined whether propofol is effective against the mechanical and metabolic damage induced by exogenously administered hydrogen peroxide in the isolated rat heart.
Methods
Rat hearts were perfused aerobically with Krebs-Henseleit bicarbonate buffer at a constant flow rate according to Langendorff's technique, while being paced electrically. Hearts were studied in control Krebs-Henseleit bicarbonate buffer, with Intralipid vehicle, with 25 microM or 50 microM propofol for 40 min, and with 50 microM propofol for 30 min followed by Intralipid for 10 min. A similar set of hearts was treated with hydrogen peroxide for 4 min, either in the absence of or beginning 10 min after Intralipid or propofol infusion. Left ventricular pressure was recorded as an index of mechanical function. The tissue concentrations of adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, and creatine phosphate were measured as indices of energy metabolism. The tissue concentration of malondialdehyde was measured to evaluate lipid peroxidation.
Results
Hydrogen peroxide (600 microM) significantly increased the left ventricular end-diastolic pressure, decreased the left ventricular developed pressure (i.e., it produced mechanical dysfunction), and decreased tissue concentrations of adenosine triphosphate and creatine phosphate (i.e., metabolic damage). Hydrogen peroxide also increased the tissue concentration of malondialdehyde. These mechanical and metabolic alterations induced by hydrogen peroxide were significantly attenuated by propofol (25 microM or 50 microM), while the increase in malondialdehyde was completely suppressed by propofol.
Conclusions
The current study demonstrates that in the isolated heart, propofol attenuates both mechanical and metabolic changes induced by exogenously applied hydrogen peroxide. The beneficial action of propofol is probably correlated with reduction of the hydrogen peroxide-induced lipid peroxidation.
Heat stress-induced protection of endothelial function against ischaemic injury is abolished by ATP-sensitive potassium channel blockade in the isolated rat heart
