Efeito do consumo de proteolisado do soro do leite em parametros do estomago e coração de ratos jovens exercitados / Intake of whey hydrolysate by the exercinsing rat and its effects on stomach and heart parameters

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Recent studies suggest that the consumption of milk whey proteins, if partially hydrolyzed, result in different physiological effect from those produced by the ingestion of the unbroken proteins. Therefore, the objective of the present work was to verify eventual metabolic alterations caused in the stomach and heart tissues of exercising Wistar rats fed an enzymatic milk whey hydrolyzate, as compared to cohorts receiving the unhydrolyzed proteins. The enzymatic activity of pepsin and those of glycogen synthase, glycogen phosphorylase, creatine kinase, as well as glycogen stores of the myocardium were thus investigated. Additionally, the perfusion of peptides through the stomach wall using capillary electrophoresis and liquid chromatography was also verified. The biological assay was conducted with 120 rats, during 42 days. The animals were divided into 12 groups (n=10), as follows: three protein sources: casein (C), protein hydrolyzate (H) and the unbroken whey protein (I), in addition to four types of physical activity: trained (T), trained-exhausted (TX), sedentary (S), sedentary-exhausted (SX) for four weeks. For creatine kinase, higher activities were observed (without significant difference) in groups T and TX, when these consumed diet H. With regard to myocardial glycogen, higher stores were found in the animals with lesser physical activity, while glycogen concentrations varied randomly in response to the diet. However, the animals that consumed diet H exhibited lower glycogen synthase activity in comparison to those that received diet I, which in turn were lower than those that received diet C. As for glycogen phosphorylase, higher values were noticed in the groups subjected to training (T) in relation to the other groups. Similarly, the animals on diet H also responded with lower activities. With regard to exhaustion time, only those groups that underwent training (TX) appeared to be more resistant to exhaustion than those that remained sedentary (SX). The enzymatic activity of pepsin did not show significant differences among groups, except for the increase of the sedentary that consumed diet H. The increase, however, disappeared when the animals were brought to exhaustion. Study of the possibility of perfusion of whey protein peptides through the stomach wall suggested that at least one peptide rich in valine promptly perfused to the external fluid. A higher number of capillary electrophoretic peaks were also observed in the stomach contents of the animals of groups SX and TX that received the hydrolyzate infusion and, by liquid chromatography, it was possible to notice that the group S stomachs had greater levels of free amino acids than the other groups. Comparing the values found for free amino acids with the total amino acids, in both the inside and outside of the stomach, it could be stated that the content of peptides formed in the stomach was considerably greater in the group infused with the hydrolyzate than with the isolate. It is concluded that chronic consumption of the whey protein hydrolyzate as the only source of protein results in enzymatic changes consistent with a more efficient physiologic state, favorable to higher physical performance, such as higher myocardial creatine kinase and lower glycogen kinase and phosphorylase activities. No significant changes in pepsin activity in the rat stomach were observed, but the readiness with which the hydrolyzate peptides accumulate and traverse the organ wall was evident. Further data to provide a better understanding of the implications of consuming prehydrolyzed proteins await investigation

ASSUNTO(S)

glicogenio glycogen pepsina pepsin milk whey proteins protein hydrolysates creatina-quinase hidrolisados de proteinas creatine kinase soro de leite

ACESSO AO ARTIGO

Documentos Relacionados