Biologic Effect of Low-Intensity Electromagnetic Radiation on Myocardium in Experimental Ischemia

Abstract

DOI: 10.17691/stm2015.7.2.06 Received May 30, 2014s.L. Malinovskaya, DSc, Professor, Department of Medical Physics and Informatics;А.P. bavrina, PhD, Associate Professor, Department of Medical Physics and Informatics;T.I. solovyova, PhD, Senior Researcher, Central Scientific Research laboratory;M.V. Rakhcheyeva, Researcher, Electron Microscopy unit, Central Scientific Research laboratory;Е.I. Yakovleva, PhD, Senior Researcher, Electron Microscopy unit, Central Scientific Research laboratory;V.А. Monich, DSc, Professor, Head of the Department of Medical Physics and InformaticsNizhny Novgorod State Medical Academy, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russian federation The aim of the investigation was to study modification of lipid peroxidation level and myocardium microstructure in rats exposed to low-intensity laser radiation (lIlR) as compared to the effects caused by broadband red light (BBRl).Materials and Methods. The research was performed on 91 white outbred male rats weighing 250 to 280 g. The experimental animals were divided in two test groups and two control ones: control group 1 (n=23), spurious irradiation without ischemia; control group 2 (n=22), ischemia + spurious irradiation; test group 1 (n=21), ischemia + exposure to lIlR; test group 2 (n=25), ischemia + exposure to BBRl. Cardiac ischemia was modelled by blocking the rats’ left coronary artery in situ for 5 min. In the test groups light irradiation was performed during 10 min immediately after the ligature removal. Helium neon laser lG-13 and self-developed luminescent fiber optic apparatus were used as light sources.Results and Discussion. Exposure of myocardium both to laser radiation and broadband light decreased the peroxidation level in the myocardium tissues. The exceptions were observed in content of trienoic conjugates in the group exposed to laser light. A more effective decrease in the level of primary peroxidation products was found in the group irradiated by BBRl.Electron microscopic study of the myocardium tissues microstructure demonstrated a reduced condition of cardiomyocytes exposed to lIlR; presence of sarcomeres dilatation, hypertrophic mitochondria and their swelling; dialation of sarcoplasmic reticulum; insignificant quantity of granule cells. At the same time, in the samples exposed to BBRl we observed no signs of sarcoplasm clearing; mitochondria were slightly swollen with preserved cristae, Golgi complex was well-marked; granule cells content in the sarcoplasm was greater than in the control group with ischemia and spurious irradiation and much greater than in the group exposed to lIlR. The dispersed chromatin nuclei contained 1 or 2 nucleoli.Conclusion. The study of cardiomyocyte subcellular structure after oxidative stress induced by ischemia and consequent reperfusion revealed adaptive changes only in the species exposed to BBRl (nuclei activation: euchromatin, nucleoli availability, mitochondria structure preservation and significant content of granule cells).The observed difference in the microstructure of the heart muscle cells in two test groups clearly demonstrates the dissimilarity in photobiomodification processes caused by laser radiation as compared to broadband red light (of the similar intensity in the light spot zone and the spectral maximum near the laser radiation line).The resulting data enable us to speak about the possibility of using low-intensity BBRl irradiation of the heart as an effective method for recovery of the heart muscle after oxidative stress caused by ischemia and reperfusion and restoration of the hemodynamic characteristics of the coronary system.Key words: low-intensity laser radiation; broadband red light; myocardium.For contacts: Monich Viktor Anatolyevich, e-mail: vam@gma.nnov.ru