Abstract:

Objective To establish a ventricular pressure-clamping method for isolatedperfused hearts of small animals, observe the effect of mechanical stimuli on cardiac electrical activities and explore the phenomena and mechanisms of cardiac mechano-electric feedback.
Methods Using the ventricular pressure-clamping method to stretch the left ventricle(LV) during the end of action potential, the effect on monophasic action potential duration(MAPD) of ventricles was observed.
Results LVMAPD90 was lengthened by 15.4%, 26.1%, 44.4％(P<0.05) comparing to the control when the left ventricle was clamped by extra stretch which was 130, 140, 150 mmHg, respectively, while LVMAPD₂₀ and LVMAPD₅₀ had no changes; There was no significant difference in RVMAPD₂₀, RVMAPD₅₀ and RVMAPD₉₀ between before and after extra inflations were applied.
Conclusion This ventricular pressure-clamping method developed by our lab can exactly mimic the changes of load in hearts under the physiological/pathophysiological conditions and can freely deliver mechanical stimuli to the ventricle, which improved the method of pressure-controlling on researching cardiac MEF at organ level; stretching the left ventricle during the end of the action potential could lengthen MAPD, slower repolarization, while the right ventricle had not the same changes, which suggested that the inflations caused a kind of inward current in the left ventricle.

Key words: ventricular pressureclamping, monophasic action potential, mechano-electric feedback