A brief regional ischemic-reperfusion enhances propofol-induced depression in left ventricular function of in situ rat hearts.

Background: Propofol is short-acting intravenous general anesthetics that reduces cardiovascular hemodynamics. The effects of propofol on intrinsic myocardial contractility, however, remain debatable. The aim of the current study was to test the hypothesis that inhibitory effects of propofol on left ventricular (LV) contractility and mechanical work capability of in situ ejecting rat hearts are attenuated after a brief regional ischemia and reperfusion.

Methods: The authors obtained steady-state LV pressure-volume loops and intermittently obtained LV end-systolic pressure-volume relation and evaluated effects of propofol on LV function by end-systolic pressure (ESPmLVV), systolic pressure-volume area (PVAmLVV) at midrange LV volume (mLVV).

Results: Propofol (5.2 +/- 0.3 approximately 11.1 +/- 3.7 microg.ml) significantly decreased ESP0.08 to 78 +/- 12% approximately 64 +/- 13% of prepropofol and PVA0.08 to 76 +/- 13%approximately 63 +/- 16% of prepropofol in normal hearts, whereas propofol at a lower concentration (4.1 +/- 1.0 microg/ml) did not. Although brief ischemic-reperfusion per se did not affect LV function, propofol after that, even at a lower concentration (4.1 +/- 1.0 microg/ml), significantly decreased ESP0.08 to 70 +/- 27% of prepropofol and PVA0.08 to 68 +/- 33% of prepropofol. Pretreatment with a protein kinase C (PKC) inhibitor, bisindolylmaleimide reduced the propofol (4.1 +/- 1.0 microg/ml)-induced greater decreases in ESP0.08 and PVA0.08 after brief ischemic-reperfusion to 94 +/- 33% and 92 +/- 39% of prepropofol. In the propofol-infused hearts after brief ischemic-reperfusion, protein kinase C-epsilon translocation to the nucleus-myofibril fraction was found.

Conclusion: In contrast to the study hypothesis, brief ischemic-reperfusion enhanced the inhibitory effects of propofol on LV systolic function; this enhancement is attributable to activation of protein kinase C.