New Method for Mechanical Work Registration of Isolated Non-Fixed Frog Heart

Abstract

The purpose of article was a presentation of the new method for mechanical work registration of an isolated non-fixed frog heart, based on dynamic determining of its bio-impedance with possibility of simultaneous ECG registration. During experiments the bio-impedance of a grass frog heart (Rana temporaria) placed in Ringer solution for coldblooded animals have been determined continually by using of the computer reographic apparatus “Reospectrum” (“Neurosoft”, Russia). For proving of the method sensitivity was performed stimulation of a heart by adrenalin in all experiments (n=10). The results were illustrated by both impedance-cardiogram (ICG) and electrocardiogram fragments recorded synchronously. It have been established that in 4 min after hormone application the heart rate rises in 50-70%. The highest rate usually was observed in 6-8 min after stimulation by adrenalin. After 8 min the heart rate became 2.5 times faster than initial parameter. “Amplitude” of contractions changes in phase too. The largest positive inotropic effect of adrenalin was observed in 4-5 min – the amplitude of ICG waves increase in 126.6% in comparison with initial point. After amplitude peak the significant decrease of waves was registered in 14-16 min after the application in comparison with initial parameter. The main technical achievement of the method for mechanical work registration of isolated heart is possibility to obtain required data characterized contractile activity of different arias of frog heart muscle easily and simply without risk of myocardium injure.