The role of energy substrates in the regulation of force-frequency relationship in the rat myocardium: the influence of ambiocor

The effect of ambiocor (15 mg/100 ml), which contains natural substrates of energy metabolism, on the contractility of papillary muscle of the right ventricle of rat heart was studied at stimulation frequencies from 0.1 to 3.0 Hz at a temperature of 30 ± 1°C (n = 7). The effect was recorded 20 min after the addition of the preparation. It was demonstrated that ambiocor causes a significant (about 70%), independent of stimulation frequency, suppression of the amplitude of isometric contractions (negative inotropic effect), which is coupled with an increase in the relative value of the rest potentiation effect (a qualitative index of calcium content in SR). The influence of the mixture leads to significant alterations in the time parameters of the “contraction-relaxation” cycle: an increase in the duration of latent period; and a decrease in the time to peak tension and half-relaxation time. The effect of the mixture is partially reversible. During washing off the preparation with the control solution, the qualitative indicators of the contractile activity of papillary muscle are substantially improved in comparison with the initial ones. The character of alterations allows one to assume that the effect of ambiocor in the papillary muscle of the rat heart is realized partly through the suppression of the activity of sarcolemmal calcium channels.