Соотношение удельного объема коллагена I и III типа в миокарде левого желудочка преждевременно родившихся крыс

Abstract

Introduction. Type I/III collagen ratio in the myocardium plays a key role in determining the biomechanical properties of the heart. The aim was to study type I/III collagen ratio of the myocardial stroma of the left ventricle in prematurely born rats. Materials and methods. The experiment included 120 Wistar rats of both sexes, which were divided into three groups. The control group included full-term animals (22 days of gestation), and groups 1 and 2 involved preterm animals (21.5 and 21 days of gestation, respectively). We used histological (Masson staining) and immunohistochemical (detection of type I and III collagens) methods to analyze the left ventricular myocardium in term and preterm rats on months 1, 1.5, 2, and 6 of the postnatal period. Results. Preterm birth leads to the development of myocardial fibrosis, whose severity correlates with the degree of prematurity. Due to preterm birth, the accumulation rate of type I collagen in the left ventricular myocardium accelerates. From month 2 of the postnatal period, the specific volume of type I collagen in term and preterm rats does not differ. An increase in the specific volume of type III collagen in the left ventricular myocardium in preterm rats is observed up to month 6 of the postnatal period. Preterm birth of rats results in decreased type I/III collagen ratio in the left ventricular myocardium in months 2 and 6 of the postnatal period. Conclusion. Preterm birth of rats leads to adaptive remodeling of the connective tissue of the left ventricular myocardium, which consists in the initial (1–1.5 months of the postnatal period) growth in the specific vol-ume of type I collagen and further (up to month 6 of the postnatal period) increase in the specific volume of type III collagen, compared to the same parameters of the myocardium of full-term animals. The decrease in type I/III collagen ratio on months 2 and 6 of the postnatal period indicates a change in biomechanical properties of the left ventricular myocardium in prematurely born rats. Keywords: preterm birth, prematurity, cardiac remodeling, myocardial fibrosis, type I collagen, type III collagen