Influence of age and nephron mass reduction on the myocardium and coronary arteries in young rats

The aim of the study - to evaluate the effects of age and renal dysfunction on the myocardium and coronary vessels in young Wistar rats. Materials and methods. The study was performed on male Wistar rats aged ~ 2.5 months. 5/6 nephrectomy (NE) was performed stepwise at intervals of one week. The observation period was 2 or 4 months after NE or sham operation. For histological examination, the heart sections were stained with hematoxylin & eosin and by van Gieson. The histological changes were studied by light microscopy and quantitatively assessed by morphometry program Videotest 5.2. Results. At intact rats aged about 6.5 months as compared to animals at the age of 4.5 months there was a clear increase in the left ventricular mass index and moderate growth of connective tissue in the myocardium (including perivascular areas). These changes were accompanied by an extension of the lumen of the intramural coronary arteries, combined with a slight decrease in the thickness of the walls of these vessels. Two 2 months after 5/6 nephrectomy (NE) pronounced spasm and early signs of thickening of the coronary artery walls took place, along with an increase of the left ventricular mass index and myocardial fibroplastic manifestations. Longer postoperative observation periods (4 months) were associated with a significant expansion of the connective tissue, increasing of the vascular wall thickness and the diameter of the vascular lumen without increase of the index of left ventricular mass. Manifestations of myocardial and coronary vessel remodeling evoked by age and renal dysfunction are not unequivocally associated with an increase in blood pressure. Conclusion. In young Wistar rats both slight increase in age and nephron mass reduction result in significant independent effects on the myocardium and its vasculature.

миокард, коронарные артерии, возраст, ремоделирование, сокращение массы действующих нефронов, rats, myocardium, coronary arteries, age, remodeling, nephron mass reduction

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