Inotropic eff ects of an isolated rat heart under the coronary perfusion with immobilized subtilisins

I n t r o d u c t i o n . Immobilized subtilisins are currently used as a fibrinolytic agent in antithrombotic drugs. The effect of immobilized subtilisins (ISs) on the contractile function of the heart has not been previously studied.
A i m . To study the effect of coronary perfusion with immobilized subtilisins (ISs) on the contractile function of an isolated rat heart in an experiment.
M a t e r i a l s a n d m e t h o d s . The study used a Langendorff model of coronary retrograde perfusion of an isolated rat heart with solutions of ISs at different concentrations. The experiment included 50 male rats. The animals were divided into 5 groups: group 1 – control (hearts perfused only with Krebs-Henseleit solution) and 4 experimental groups – hearts perfused with a solution of ISs at concentrations of 170, 340, 510 and 1020 IU/l, respectively. The contractile function (inotropic effect) of the isolated rat heart was assessed in terms of the pressure developed by the left ventricle (LVP).
R e s u l t s . Perfusion of an isolated rat heart with a solution of ISs for 40 min causes a positive inotropic effect in all experimental groups. At a concentration of 170 IU/l, the effect is observed from the 10th minute, at higher concentrations – from the 5th minute. The duration of the effect’s rising when using ISs in the dose range of 170–510 U/l manifests itself up to the 20th minute, and when using a dose of 1020 U/l – up to the 30th minute. Then there is a weakening of the inotropic effect. In groups of animals with the introduction of immobilized subtilisins at a concentration of 340–1020 U/l, there is a decrease of LVP by the 40th minute, but the values of this indicator remain higher compared to the control group.
C o n c l u s i o n . Perfusion of the isolated heart with a solution of ISs increases the contractile activity of the isolated heart. When the heart is perfused with ISs, there is an increase of LVP. The inotropic effect is dose-dependent at various time points

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