The effects of high-dose epinephrine combined with isoprenaline on isolated rabbit heart and cardiomyocytes after cardioversion of ventricular fibrillation.

The effects of high-dose epinephrine (HDE) combined with isoprenaline (Iso) on myocardial hemodynamics of isolated rabbit heart were studied. The electrophysiology and L-type Ca2+ channel of single ventricular myocyte after cardioversion of ventricular fibrillation were determined. The results suggest that parameters of hemodynamics were significantly enhanced by HDE+Iso than that of HDE (p < 0.01). The OS and Vmax of HDE+Iso increased 83.7 and 10.15% respectively compared to HDE alone. The APF of HDE+Iso is much more rapid than that of HDE (138.38 +/- 9.96 vs. 55.58 +/- 8.63 min(-1), p < 0.001). The APD50 and APD90 of HDE+Iso were significantly decreased; HR was increased (134.16 +/- 1.48 vs 62.20 +/- 6.25 min(-1)); and the amplitude current of through L-type Ca2+ channel was reduced but was significantly higher than the control. We conclude that HDE+Iso can improve the hemodynamics and improve electrophysiology of cardiomyocytes after cardioversion of ventricular fibrillation which is likely interrelated with I(Ca). The combined use of epinephrine and isoprenaline for cardiopulmonary resuscitation of primary ventricular fibrillation may be beneficial when employed in clinical situations.