Dose-dependent, and long-lasting, effects of repeated intravenous injections of calcium on the canine secretin-stimulated pancreatic juice secretion.

The effects of repeated intravenous calcium administration on pancreatic juice secretion were investigated in four Thomas fistula dogs. During stimulation by 1.0 U kg-1h-1 GIH secretin, three Ca doses were administered: 2, 4 and 8 mu mol kg-1 min-1 during 1 h, saline being used in control tests; one dose only was tested per day. It was found that Ca administration induced both acute and long-lasting effects. Acute effects were characterized by an increased response to secretin stimulation. Fluid, HCO3(-), protein and Ca outputs increased significantly in a dose-dependent manner, the increase of protein output being the most dramatic. Long-lasting effects, until now unrecognized, were characterized by a progressive increase of protein secretion during the first hour of secretin stimulation. This increase kept going during the 3 months of repeated calcium injections. Although protein plugs were observed in the juice, sometimes stopping the flow of juice, no pancreatic lesion was found. A second protocol showed that, after discontinuing calcium injections, the long-lasting effects decreased progressively, but protein hypersecretion was still significant 3.5 months later. The importance of these findings regarding chronic pancreatitis due to hyperparathyroidism is discussed.