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

Capillary growth in anemia-induced ventricular wall remodeling in the rat heart

To determine whether anemia-induced cardiac hypertrophy affects ventricular size and shape and the component structures of the capillary network of the left and right ventricles, young male rats were fed an iron- and copper-deficient diet for 7 weeks. By that time, blood hemoglobin content fell to 5 +/- 1 g/dl, and packed cell volume fell to 18 +/- 3%. To further characterize the implications of anemia, red blood cell number, hemoglobin corpuscular content, systemic arterial pressure, heart rate, and blood viscosity were measured. Moreover, the changes in ventricular weights were analyzed in terms of the alterations in ventricular wall area and ventricular wall thickness to establish the impact of the elevation in load associated with a high cardiac output state on ventricular remodeling. The quantitative properties of the capillary circulation were also examined biventricularly by low power electron microscopic morphometry to evaluate the adaptive growth potential of the coronary microcirculation in this form of cardiac hypertrophy. Anemia was found to interfere with the production of red blood cells and their mean corpuscular hemoglobin content and resulted in a 40% reduction in blood viscosity and a 12% and 27% decrease in systolic and diastolic blood pressure, respectively. The changes in heart rate were not statistically significant. In comparison with control animals, heart weight increased by 50%, but the enlargement in right ventricular mass (65%) was greater than that of the left ventricle (47%). Ventricular hypertrophy occurred with increases in wall area and wall thickness although the former increased consistently more than the latter in either ventricle. Tissue growth was accompanied by a 60% lengthening of the capillary network, which in combination with an increase in capillary diameter resulted in a 65% and 34% expansion in capillary luminal volume and 56% and 20% larger luminal surface density in the left and right sides of the heart, respectively. In conclusion, hypochromic microcytic anemia leads to eccentric ventricular hypertrophy with a significant amount of capillary proliferation that may tend to protect the myocardium from the increased potential for ischemic injury.

Effects of malnutrition on rat myocardial beta-adrenergic and muscarinic receptors

Malnutrition, as well as malignancy, induces alterations in heart metabolism and performance. Previous studies have implicated adrenergic mechanisms as the cause. The present study was undertaken to investigate if the adenylate cyclase system in the rat heart was affected by malnutrition. Three different animal groups with malnutrition were compared with a control group: rats with acute starvation for 14-96 hours, rats with protein-calorie malnutrition for 2 weeks, and rats with tumors. Stimulation by beta-adrenergic receptors and inhibition by muscarinic receptors of adenylate cyclase activity were not altered by malnutrition. However, conditions used for in vitro adenylate cyclase determinations were, of necessity, not physiological. Neither did the number of beta-adrenergic and muscarinic receptors change. When competition-binding experiments were performed, differences comprising agonist affinity and affinity state distribution were noted among the groups. The myocardial beta-adrenergic receptors formed a reduced number of high-affinity sites in all groups as compared with the control rats. All high-affinity sites displayed a more than 10-fold increase in affinity toward isoproterenol and an impaired sensitivity to guanine nucleotides except in heart membranes derived from rats starved less than 48 hours. While the protein-calorie restricted and the tumor-bearing rats had myocardial beta-adrenergic receptors that were unresponsive to guanine nucleotides, after 48 hours of starvation the rats exhibited an attenuated guanine-nucleotide-induced affinity shift. No changes associated with malnutrition in myocardial membrane levels of the of the stimulatory guanine-nucleotide-binding protein were detected by cholera-toxin-induced ADP-ribosylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial hypertrophy, cardiac and urinary catecholamines during severe ethanol intoxication and withdrawal

Cardiomegaly was observed in rats severely intoxicated with ethanol for a 4 day period. It was apparent at 48 hours of treatment, a time at which cardiac protein was elevated and continued into withdrawal. During a 4 day abstinence period the degree of hypertrophy declined towards normal. Cardiac noradrenaline was reduced at the 48 hour time of intoxication, then increased gradually in the further experimental period. As the cardiac hypertrophy occurs at a time that urinary catecholamines are elevated and the adrenal medulla is intensely stimulated, it is proposed that increased levels of circulating catecholamines are largely responsible for the enlargement of the heart.

Kynurenines and seizures

Recent data and concepts concerning the convulsant effects of kynurenines, neuroactive metabolites of tryptophan, in mice, rats, and frogs are reviewed. Myoclonic seizures of the hindlegs are induced in mice by l- and d,l-kynurenine. Both l- and d,l-kynurenine exhibit a selective synergism with strychnine. The convulsant effect of l-kynurenine is selectively antagonized by taurine, less selectively by l-glycine, and not at all by gamma-aminobutyric acid (GABA) or the GABA agonist muscimol. Derivatives of GABA and some standard anticonvulsant drugs alter seizures induced by l-kynurenine and quinolinic acid in different ways. The involvement of brian kynurenines in the genesis of epileptic seizures is suggested.

Intestinal neurohormones in protein-deficient rats

The levels of noradrenaline, adrenaline, and serotonin in the jejunum and ileum of weanling rats fed protein-free (deficient) and high-protein (control) diets were analyzed. The concentration of noradrenaline of the deficient rats was markedly increased, both in the jejunum (0.430 +/- 0.039 microgram/g vs. 0.188 +/- 0.019 microgram/g in the control animals, +228%, P < 0.001) and in the ileum (0.492 +/- 0.041 microgram/g vs. 0.212 +/- 0.014 microgram/g in the control rats, +232%, P < 0.001). However, the levels of adrenaline and serotonin were unaltered in deficient rats as compared to controls, both in the jejunum (0.049 +/- 0.009 microgram/g of adrenaline and 1.233 +/- 0.178 microgram/g of serotonin vs. 0.047 +/- 0.006 microgram/g of adrenaline and 1.364 +/- 0.131 microgram/g of serotonin in the controls) and in the ileum (0.027 +/- 0.005 microgram/g of adrenaline and 0.902 +/- 0.150 microgram/g of serotonin vs. 0.038 +/- 0.006 microgram/g of adrenaline and 1.118 +/- 0.192 microgram/g of serotonin in the controls). In view of these results, it can be speculated that the abdominal distension and the reduced intestinal motility usually seen in the states of protein malnutrition could be caused, at least in part, by the accumulation of noradrenaline in the intestine.