Peripheral glucose and potassium transport after glucose ingestion in normal subjects

This study was designed to quantify forearm potassium uptake or release in the postabsorptive state and after an oral glucose challenge, and if there is association of potassium uptake with glucose and free fatty acids (FFA) metabolism in peripheral tissues of normal subjects. Nine healthy volunteers (4M and 5F) were studied after an overnight fast (12-14 h) and during 3 hours after ingestion of 75 g of glucose. The forearm glucose uptake rate reached the maximum at 60 minutes (0.985 mg/100 ml forearm.min), declining to the basal levels at the end of the 3 h of study. Although heterogeneously in the postabsorptive state, potassium moves out of the forearm muscle into the venous blood in normal individuals. After glucose ingestion, the potassium release diminished and there was also potassium uptake during the last hour of the study. The arterial FFA levels decreased significantly after the glucose load. In conclusion, the results of this study showed that in peripheral tissues: 1) during the first 2 h after the ingestion of 75 g of glucose there was a reduction in potassium release; 2) potassium uptake only occurred in the last hour when insulin levels were slightly higher, plasma glucose were similar and FFA were lower than in the postabsorptive period; 3) there was a clear dissociation between potassium and glucose uptake.