The electrophysiological effects of alcoholized rhubarb solution in feline heart in vivo

The effects of Chinese medicine, alcoholized rhubarb, on cardiac electrophysiology and contractile force were studied by using monophasic action potential (MAP) techniques with an improved pressure-electrical transducer epicardial electrode and/or an endocardial pressure-contact electrode catheter in 27 feline hearts in vivo. The results of the experiments were as follows: 1) Alcoholized rhubarb solution (1.5 g/kg) caused a greater increase in the MAP amplitude (from 18.8 +/- 0.62 mV to 26.7 +/- 3.87 mV, p < 0.01), in the MAP maximum rate of rise of phase 0 (from 1.7 +/- 0.13 V/sec to 2.6 +/- 0.43, p < 0.01), and in the MAP duration at 50% and 90% repolarization (from 194.3 +/- 14.00 msec to 216.3 +/- 6.30 msec and from 238.8 +/- 21.41 msec to 280.5 +/- 14.68 msec, respectively, p < 0.01), and a decrease in the heart rate (from 130.8 +/- 12.10 bpm to 110.8 +/- 10.35 bpm, p < 0.01) in the epicardial monophasic action potentials after rhubarb solution administration for 1 min. 2) The ventricular contractile force of the feline heart in vivo was also significantly increased (11.1 +/- 0.52 g to 14.0 +/- 1.41 g, p < 0.01) by rhubarb solution. 3) A dose-dependent relation of alcoholized rhubarb solution was found and indicated that lower doses (1.0-1.5 g/kg) had an excitatory effect, while a higher dose (2.0 g/kg) had inhibitory or toxic effects on the intact feline heart. The present study provides evidence that Chinese rhubarb solution has electrophysiological effects on the feline heart in vivo.