Development of cardioprotective effect of chronic continuous hypoxia in rats with induced metabolic syndrome

Abstract

   Background. It is known that adaptation to chronic continuous hypoxia leads to a pronounced cardioprotective effect. The efficiency of acute adaptation to hypoxia is reduced in metabolic syndrome. However, the effectiveness of the myocardial infarct size-limiting effect of chronic continuous hypoxia in metabolic syndrome remains an understudied fact.   The aim. To study the effectiveness of the development of the myocardial infarct size-limiting effect of chronic continuous hypoxia in rats with metabolic syndrome.   Materials and methods. The study was carried out on 43 Wistar rats. Adaptation of animals to chronic hypoxia was performed during 21 days in a hypoxic chamber (12 % O2, 0.3 % CO2). Metabolic syndrome was modeled by keeping rats on a high-carbohydrate and high-fat diet (proteins 16 %, fats 21 %, carbohydrates 46 % (including fructose 17 %), cholesterol 0.125 %, cholic acid 0.5 %) for 12 weeks with replacement of drinking water with 20% fructose solution. Coronary occlusion-reperfusion was performed in vivo. The effect of chronic hypoxia and metabolic syndrome on myocardial infarct size was assessed.   Results. It was found that myocardial infarct size in rats after chronic continuous hypoxia was 38 % less than in animals of the control group. In rats which were kept on a high-carbohydrate and high-fat diet we observed the obesity, decreased glucose tolerance, increased serum triglycerides level, and hypertension. Adaptation to chronic continuous hypoxia in animals on a high-carbohydrate and high-fat diet improved carbohydrate metabolism, but did not affect the severity of other metabolic disorders. At the same time, the myocardial infarct size-limiting effect of chronic hypoxia was not observed in rats with metabolic syndrome.   Conclusion. Metabolic syndrome eliminated myocardial infarct size-limiting effect of chronic continuous hypoxia.