Effect of protein-calorie malnutrition on catecholamine levels and weight of heart in rats.

Catecholamine levels and weight of heart were studied in rats subjected to protein-calorie malnutrition and after a period of nutritional rehabilitation. Rats given a protein deficient diet (4% protein) for periods of 6 and 12 weeks showed a severe restriction of body weight gain. Nevertheless, even though the measured heart weight of deficient rats was significantly lower than the respective controls (16% protein), the deficient rats incurred "real" cardiac enlargement since the mean heart weight of the equal body weight controls was significantly different from that of the deficient animals. The mean heart weight of rats fed a high-protein diet for 6 weeks thereupon a 6-week period of protein deprivation was still less than that of controls, and the heart ratio was still greater than that of controls. However, the heart weight of rehabilitated rats was not significantly different from that of equal body weight controls. Serum protein and albumin levels in dificient rats were significantly decreased in comparison to rats fed a high-protein diet. While the serum protein levels of rehabilitated rats were lower than those of controls, the albumin levels were not different. The protein-calorie malnourished rats, which received a low-protein diet for 6 and 12 weeks, showed a significant increase in myocardium noradrenaline concentration. After a period of nutritional rehabilitation this change did not persist. These catecholaminergic alterations in heart may be responsible, at least in part, for the different cardiac abnormalities described as a result of protein-calorie dietary deficiency. It may also explain the "real" cardiac enlargement observed in deficient rats, according to the hypothesis that noradrenaline may be the ultimate myocardial hypertrophy hormone.