RESUMO
It is generally accepted that exercise induces a decrease in splanchnic circulation, because of the increase of blood in working skeletal muscle. On the other hand, ingestion of a meal increases blood flow in splanchnic circulation. However, it remains to be clarified whether splanchnic circulation decreases due to exercise after ingestion of a meal. The present study examined the effect of different intensities of cycling exercise after ingestion of a carbohydrate-drink on portal venous blood flow, blood glucose, serum insulin and plasma catecholamine concentrations. Six volunteers ingested 200 ml of martodextrine solution (12%) [M (200) ] before 20 min exercise sessions of 30% maximal oxygen uptake (VO<SUB>2</SUB>max) and 60% VO<SUB>2</SUB>max. Before and after the exercise sessions, portal venous blood flow was measured by a combined ultrasonic system of an electronic sector scanner and pulsed Doppler flowmeter. Portal venous blood flow in the exercise at 30% VO<SUB>2</SUB>max increased due to the M (200) ingestion. However, a decrease in portal blood flow resulting from exercise at 60% VO<SUB>2</SUB>max was observed in spite of a M (200) ingestion compared with portal blood flow after both rest and the exercise at 30% VO<SUB>2</SUB>max. Immediately after exercise, an increase in blood glucose and serum insulin level was shown for 30% VO<SUB>2</SUB>max with M (200), but not 60% VO<SUB>2</SUB>max. In addition, plasma epinephrine concentration after taking M (200) did not increase as a result of either exercise intensity.<BR>These results suggest that the response of portal venous blood flow caused by carbohydratedrink ingestion immediately before exercise is influenced by exercise intensity, and it corresponds to the changes in blood glucose, serum insulin and plasma epinephrine. We concluded that ingestion of food, rather than exercise, has a regulatory action in splanchnic circulation in low intensity exercise.
RESUMO
The purpose of this study was to investigate the effects of different intensities of exercise on α-tocopherol and thiobarbituric acid reactive substance (TBARS) levels in the plasma and liver of rats. Male Wistar rats were divided into a sedentary control group and exercise groups. The exercise groups were forced to exercise by treadmill running at 30%, 60% and 80% of maximum oxygen uptake (VO<SUB>2</SUB>max) for 120 minutes. Some animals in each exercise group were sacrificed immediately and others at 6 hours after the exercise period, α-Tocopherol levels in the plasma and liver were analyzed by HPLC. Plasma α-tocopherol levels of rats sacrificed immediately after the exercise period decreased significantly in the 60% and 80%VO<SUB>2</SUB>max groups compared to controls. In all exercise groups, plasma α-tocopherol levels were significantly higher 6 hours after the exercise period compared to those sacrificed immediately after the exercise period. Liver a -tocopherol levels were also lower in all exercise groups 6 hours after the exercise period, especially in the 80% VO<SUB>2</SUB>max exercise group. There were no differences in TBARS levels between the control and exercised groups. These results indicate that acute exercise induces oxidative changes in the liver, but the liver is able to compensate by increasing the consumption and release of α-tocopherol to neutralize any damage.
RESUMO
In this study, we investigated the effect of acute exercise on the mitochondrial structure of hepatocytes surrounding the terminal hepatic venule (zone III) in the rat liver acinus. Male SD rats were assigned to a resting group (n=8) and to running groups ran on a motor-driven treadmill for 100 min (n = 8) or did continued running beyond 100 min until exhaustion (n = 5) . Plasma guanase activity was increased with duration time of exercise. The arterial ketone body rate (AKBR) increased during the 100 min of running, but the AKBR significantly diminished with exhaustive running as compared with that for 100 min of running. Although there was no change in the mitochondrial structure of hepatocytes in the perportal area (zone I) during exhaustion, remarkable swelling was observed in that in zone III.<BR>These results suggest that acute running affects mitochondrial structures in zone III, and that this might be a hypoxia zone during exercise.