Effect of chronic renal failure on heart. Role of secondary hyperparathyroidism

This study examined the effects of chronic renal failure in rats with and without parathyroid glands on myocardial energy production, transfer and utilization as well as on cardiac index. Chronic renal failure was produced by 7/8 nephrectomy in rats weighing between 240 and 350 g with intact parathyroid glands (CRF-control) and in parathyroidectomized (CRF-PTX) rats maintained normocalcemic. The data were compared to results obtained in intact rats and in normocalcemic parathyroidectomized rats with normal renal function. There were significant (p less than 0.01) decrements in myocardial content of ATP and creatine phosphate, mitochondrial oxygen consumption, and in the activity of both mitochondrial and myofibrillar creatine phosphokinase in CRF-control rats as compared to normal animals. The myocardial calcium content and the 45Ca uptake in CRF-control rats were significantly (p less than 0.01) higher than in normal rats. In CRF-PTX animals, the myocardial content of ATP, mitochondrial oxygen consumption, 45Ca uptake and calcium content were normal, but PTX did not normalize the activity of mitochondrial and myofibrillar creatine phosphokinase. Parathyroidectomy in rats with normal renal function was associated with a significant reduction in the activity of creatine phosphokinase of myocardial mitochondria and myofibrils. There was a significant (p less than 0.01) decrease in cardiac index in CRF-control rats as compared to normal animals, and cardiac index did not return to normal in CRF-PTX rats.(ABSTRACT TRUNCATED AT 250 WORDS)