Cardiac function during protein malnutrition and refeeding in the isolated rat heart.

In an attempt to elucidate the effect of protein restriction and subsequent refeeding on cardiac muscle function, 133 rat hearts were studied on a Langendorff perfusion apparatus: 19 normal controls, 55 rats during 6 weeks of protein restriction, and 59 rats during 6 weeks of refeeding following starvation. During starvation animals lost 14.3% of body weight and 12.8% in heart weight, both to be gained upon refeeding. Both developed force and force velocity tended to decrease in starving rats compared to control or refeeding rats. This trend was present at time 0, but more so after 60 min of perfusion. Furthermore, these differences became even more obvious and significantly different at the higher heart rates of 300 and 400 beats/min, and less so at 100 or 200 beats/min. These protein malnutrition-associated cardiac function derangements reversed almost completely to normal upon refeeding.