Effects of glucose feeding on renal electrolyte and H+ transport

Changes of urinary pH, titratable acidity, ammonium, bicarbonate and PCO2, as well as plasma insulin and various plasma and urine electrolytes were studied in 15 normal individuals during a 5-hr glucose tolerance test. After glucose ingestion, urine pH and bicarbonate excretion rose while urine titratable and total acidity, ammonium, Na, K, Cl, phosphorus and PCO2 fell significantly. Serum bicarbonate rose while serum potassium, phosphorus, and anion gap decreased following oral glucose administration. Glucose feeding and the resultant rise in insulin are, therefore, associated with a considerable reduction in urine acidity and Na, K, Cl, and phosphorus excretion. While a significant fall in urinary Na, K and phosphorus has been shown to occur following glucose and insulin administration, their effect on renal H+ excretion in man has not been investigated previously. The mechanism of the observed fall in urine acidity is not clear and requires further investigation.