EFFECTS OF PARATHYROID-HORMONE ON PANCREATIC EXOCRINE SECRETION

The role of parathyroid hormone (PTH) and calcium on pancreatic exocri ne secretion were observed using sham-operated and parathyroidectomize d dogs. First, exocrine secretion of the pancreas stimulated with secr etin and cholecystokinin octapeptide (CCK-8) was examined in vivo 3 we eks after parathyroidectomy. Secondly, perfusion experiments of isolat ed pancreas in the sham-operated and parathyroidectomized dogs were ex amined. In one experiment, volume of pancreatic juice and bicarbonate output, but not amylase output, was decreased in the parathyroidectomi zed dogs compared with those in the sham-operated dogs; no participati on of calcium in exocrine secretion was revealed. In another experimen t, high doses of PTH evoked increases of pancreatic juice and bicarbon ate output without changing amylase output; as before, no participatio n of calcium in the exocrine secretion was observed. We conclude that (a) PTH increases volume of pancreatic juice and bicarbonate output, a nd (b) pancreatic exocrine secretion is modified by direct effect of P TH, and the pancreatic ductular cells, not the acinar cells, are the t arget for PTH.