Low intensity exercise dose not repress the increase in portal venous flow after a feeding

Abstract

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 (V̇O2max) and 60% V̇O2max. 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% V̇O2max increased due to the M (200) ingestion. However, a decrease in portal blood flow resulting from exercise at 60% V̇O2max was observed in spite of a M (200) ingestion compared with portal blood flow after both rest and the exercise at 30% V̇O2max. Immediately after exercise, an increase in blood glucose and serum insulin level was shown for 30% V̇O2max with M (200), but not 60% V̇O2max. In addition, plasma epinephrine concentration after taking M (200) did not increase as a result of either exercise intensity. These results suggest that the response of portal venous blood flow caused by carbohydrate-drink 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.