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

Abstract

Abstract 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 increased 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.