Аннотация:The impedance method of pre-ejection period(PEP) evaluation had been adapted for a small animal studyand validated with a Millar-type pressure sensor inserted intoaorta near the aortic valve or in the left ventricle. A strongcorrelation (r=0.95) was found between the PEP values determinedby the impedance and micromanometer methods. Thedifference between the PEP estimates was about 5 ms. A significantcorrelation (r=0.75-0.78) was also found between the PEPand invasive indices of left ventricular contractility, dP/dt|maxand dP/dt|max/P. It was observed for a variety of the baselinestates added with those during dopamine or ketamine injections.The contractility changes induced by a number of substanceswere evaluated by the invasive and impedance methods,which showed very similar time course of the responses. Meanwhile,the diastolic filling of the heart or changes in the arterialpressure during the tilt test or caused by a hypotensive agentmay also affect PEP. Our findings suggest that impedancemethod can provide an accurate estimation of PEP changes inanimal experiments. So, it can be a useful tool for quantifyingpotential inotropic effects of pharmacological agents. However,it should be also taken into consideration the dependency of PEPon the preload and afterload conditions, especially, when vasodilationeffects persist.