RESUMO
BACKGROUND: Free radicals and associated oxidative stress play an important role in the causation and subsequent complications of diabetes mellitus. Type I diabetes can be induced in experimental animals by administration of streptozotocin which causes selective destruction of B islet cells, probably by a free radical mediated mechanism. The objective of this study was to determine the effect of administration of alpha-tocopherol two weeks before and two weeks after streptozotocin injection on contractility and glucose uptake of rat hemidiaphragm. MATERIAL/METHODS: Male Wistar rats were used for this experiment. In the first phase, all the rats received an ordinary diet, while some were given alpha-tocopherol; in the second phase, diabetes was induced with streptozotocin, while the animals in the experimental group were given alpha-tocopherol two weeks before and two weeks after diabetes induction. RESULTS: Streptozotocin decreased the height of the indirect contraction and the time for 50% decrease in height of contraction of indirect responses. At the same time, the glucose uptake of the diaphragm muscle was also decreased. Administration of alpha-tocopherol (600 mg/kg-1, i.m.) ameliorated the inhibitory effect of diabetes on the skeletal muscle and reversed the decrease in time (s) of the 50% decrease in the height of contraction of the indirect responses of the rat hemidiaphragm preparation. Additionally, alpha-tocopherol increased glucose uptake by diaphragm muscles towards control level. CONCLUSIONS: Alpha-tocopherol supplementation probably protected against the inhibitory effect of oxidative stress observed in diabetes mellitus and contributed to improved contractility.
