Effect of intravenous infusion of hypertonic glucose solutions on pancreatic HCO3secretion

Abstract

To examine why i.v. infusion of hypertonic nonelectrolyte solutions inhibit pancreatic HCO3- secretion, the relationship between pancreatic HCO3- secretion and plasma pH was examined before and following i.v. infusion of hypertonic glucose to 5 anesthetized, secretin infused (2.7 CU[clinical unit]/kg body wt h-1) pigs. Hyperglycemia (plasma glucose 103 .+-. 6 mmol/l) did not significantly change plasma pH, Na+, K+, Cl- and HCO3- concentrations. Hyperglycemia reduced pancreatic water flux by 48 .+-. 5% and raised pancreatic juice HCO3- concentration by 43 .+-. 4 mmol/l. Concurrently, HCO3- secretion fell by 34 .+-. 5%. Acidosis, produced through i.v. HCl infusion and CO2 addition to inspired air, reduced HCO3- secretion by 40 .+-. 6 .mu.mol/min and 30 .+-. 5 .mu.mol/min per 0.1 pH unit reduction in plasma pH before and during hyperglycemia, respectively, and abolished HCO3- secretion at an estimated plasma pH of 6.51 .+-. 0.06 before and a pH of 6.63 .+-. 0.05 during hyperglycemia. Hypertonic glucose infusions apparently inhibit pancreatic water flux and cause an increase in pancreatic juice HCO3- concentration which may inhibit HCO3- secretion through an effect on acid-base balance in secretory cells.