The role of calcium in pancreatic secretion and disease

Abstract

Calcium enters the pancreatic juice from two sources, one fraction associated with enzyme protein and another small fraction presumably by diffusion. The calcium concentration in pancreatic juice is lower than in plasma. It decreases with high flow rates and increases asymptotically to plasma concentration with low rates. In chronic pancreatitis calcium concentration is raised in the secretin-stimulated juice. After pancreozymin in moderate chronic pancreatitis it is low but in severe stages of the disease it is high signalling total dissociation from the entrance of enzyme protein, which is very low in these cases. Hypercalcemia stimulates enzyme secretion in the pancreas, hypocalcemia inhibits it. Calcium is essential for intracellular processes associated with secretion, the exact place in the sequence of "stimulus-secretion-coupling" still being unknown. Calcitonin as one of the hormones which regulates calcium homeostasis, inhibits secretion of enzymes but not of fluid and bicarbonate. The action of the parathyroid hormone on the exocrine pancreas is unknown. In primary hyperparathyroidism with chronic hypercalcemia acute and chronic pancreatitis occur 10 to 20 times more frequently than in the general population. In acute pancreatitis of whatever origin hypocalcemia is atypical feature of the disease indicating bad prognosis. The mechanism of its development is still unclear. In chronic pancreatitis the forming of calcified stones in the ducts is typical in cases associated with alcoholism, with protein malnutrition and with primary hyperparathyroidism. But it occurs also in cases with unknown etiology signalling a more general pathophysiological phenomenon. The calcium salts form a precipitate on protein plugs in the juice, which have been observed even in early stages of the disease in the small and larger ducts of the gland.