Effect of plasma H+-ion concentration on pancreatic HCO-3 secretion

The relationship between the rate of pancreatic HCO-3 secretion and plasma H+-ion concentration was investigated in 15 pentothal anesthetized, secretin infused pigs (1.8 C.U./kg b.w. h-1, intravenously) during acute metabolic and respiratory acid-base disturbances. Pancreatic HCO-3 secretion increasd to 196 +/- 10% of control during alkalosis and fell to 41 +/- 4% of control during acidosis. Partial metabolic compensation of respiratory acidosis restored HCO-3 secretion to 87 +/- 6% of control. A proportional relationship was found between HCO-3 secretion and plasma pH. Different, proportional relationships were found between HCO-3 secretion and plasma HCO-3 concentration during metabolic and respiratory acid-base changes. HCO-3 secretion was independent of H+-ion concentration in pancreatic juice. Plasma H+-ion concentration, therefore, seems to determine the rate of pancreatic HCO-3 secretion. This finding supports the hypothesis that a proton pump is responsible for pancreatic HCO-3 secretion.