Ontogenetic Features of Changes in the Calcium-Accumulating Ability of the Sarcoplasmic Reticulum of the Myocardium in Rats with Postinfarction Cardiosclerosis

Physiological aging, ischemia, and progressive cardiac hypertrophy can affect the contractile function and calcium homeostasis of cardiomyocytes. The goal of this study was to investigate the calcium-accumulating capacity of the sarcoplasmic reticulum in conditions of chronic myocardial ischemia in rats of different ages. The experiments were performed on 60 male rats of three ages: 4, 12, and 24 months. Each age group included 10 control (sham-operated) and 10 experimental animals, which had simulated postinfarction cardiosclerosis (PICS) by coronary occlusion. The state of intracellular calcium homeostasis was assessed by performing a post-rest test on muscle strips from the papillary muscles of the left ventricle of the heart. It was shown that with an increasing age of animals, the strength of the contractile response of muscle strips following the rest period decreases. Postinfarction myocardial remodeling in rats aged 4 and 12 months leads to degradation of the post-rest contractile response. Muscle strips of 24-month-old PICS rats exhibited post-rest potentiation at the level of sham-operated controls in the age group.