Method for assessing myocardial damage under conditions of perfusion of an isolated heart according to the Langendorff method

One of the leading mechanisms for the development of a severe cardiovascular pathology is the intensification of free radical processes. With a decrease in the activity of the antioxidant defense, the accumulation of free radicals in the body and, as a consequence, the development of the oxidative stress is natural. The registration of the severity of processes that impair the effectiveness of the antioxidant protection, with the subsequent development of an oxidative stress, can serve as a new reliable method for assessing the degree of a myocardial damage. The aim of the work was to develop a method for assessing the degree of ischemic and ischemia-reperfusion kinds of damage to the myocardium based on the activity of free radical processes in cardiomyocytes. Materials and methods . All the experimental work under in vivo conditions was performed on 50 white sexually mature mongrel male rats. The physiological and morphological parameters of the hearts, biochemical parameters and the lipid peroxidation level of the perfusate were assessed. The changes in the level of the perfusate lipid peroxidation were assessed in a simple model system simulating the lipid peroxidation. The registration of luminescence was carried out using a chemiluminometer KHLM-003 (Russia). Luminol (5-amino-2,3-dehydro-4-phthalazinedione) was used to detect the reactive oxygen species. Results . With an increase in the ischemia duration and, as a consequence, the degree of the myocardial damage, an increase in the values of the lipid peroxidation determined by chemiluminescence is observed. When simulating 30 minutes of ischemia, necrosis is formed; it accounts for 8.9% of the total heart volume. With an increase in the ischemia duration to 60 minutes, the necrosis zone increases by 1.4 times ( p <0.05), and the light sum of luminescence increases by 9.4% ( p <0.05) relative to the 30-minute ischemia. A maximum decrease in pH is recorded at the 5 th minute of the reperfusion. Next comes the restoration of pH values, and at the 10 th minute, there is no longer any statistical difference between the initial and reperfusion values (7.37 vs 7.04 at p >0.05). In turn, the activity indicators of cytolysis enzymes (lactate dehydrogenase [LDH] and creatine phosphokinase-MB [CPK-MB]) show a similar pH trend of the growth in the first minutes of the reperfusion, followed by a decrease in the initial values, which is most likely due to the “washing out” of metabolic products. At the same time, the “freeze–storage (14 days)–defrost” cycle does not affect the indicator of the lipid peroxidation activity. Conclusion. A new method for assessing a myocardial damage during the perfusion of an isolated heart using the Langendorff method, based on the use of the luminol-dependent iron-induced chemiluminescence of the lipid peroxidation level of the perfusate obtained before and after the perfusion of an isolated heart, can become one of the most effective methods for assessing the damage to the myocardial structure.

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