ELECTROPHYSIOLOGIC PROPERTIES OF ISOLATED ADULT CARDIOMYOCYTES FROM SEPTIC RATS

In this study, we examined the effect of sepsis on the electrical prop erties of isolated ventricular myocytes. Sepsis was induced by cecal l igation and puncture (CLP). The control rats were sham-operated. Membr ane potentials and ionic currents in isolated cardiac myocytes were me asured by the tight-seal, whole-cell patch-clamp technique. The result s show that the resting membrane potentials of heart cells were signif icantly lower in the septic group (18 hr post-CLP) than those in the c ontrol group. However, there was no significant difference in action p otential duration of 50% and 90% repolarization between the two groups of cells. In voltage-clamp experiments, isoproterenol (10 nM), a beta -adrenergic agonist, caused an increase in L-type calcium current (I-C a,I-L) in a similar magnitude in myocytes isolated from the control an d septic rats. Furthermore, isoproterenol failed to modify the time co nstants for I-Ca,I-L inactivation and the overall shape of current-vol tage relationship for both groups of cells. These results indicate tha t formation of a GR seal and subsequent tight-seal whole-cell recordin g with patch-clamp technique can be performed in heart cells derived f rom CLP-induced septic rats, and that septic rat heart is capable of r esponding effectively to beta-adrenergic stimulation. (C) 1993 Wiley-L iss, Inc.