[en] The purpose of this study was to compare the hemodynamic effects of pentobarbital and propofol and their effects on cardiovascular adaptation to an abrupt increase in left ventricular afterload. Experiments were performed in 12 open-chest pigs instrumented for measurement of aortic pressure and flow, and left ventricular pressure and volume. In one group (n = 6), anesthesia was obtained with sodium pentobarbital (3 mg x kg(-1) x h(-1)), and, in the second group B (n = 6), with propofol (10 mg x kg(-1) x h(-1)). Both groups received sufentanil (0.5 microg x kg(-1) x h(-1)) and pancuronium bromide (0.1 mg x kg(-1)). Left ventricular function was assessed by the slope of end-systolic pressure-volume relationship and stroke work. After baseline recordings, left ventricular afterload was increased by aortic banding. The cardiovascular adaptations triggered by the aortic banding, such as tachycardia, vasoconstriction, and augmentation of myocardial contractility were prevented with propofol, suggesting interference with the baroreflex. Increase in left ventricular afterload decreased mechanical efficiency, regardless of anesthetic agent. These results showed that pentobarbital at 3 mg x kg(-1) x h(-1) has less deleterious hemodynamic effects than propofol at 10 mg x kg(-1) x h(-1).