Stimulation of gastrin secretion in the pig by parathyroid hormone and its inhibition by thyrocalcitonin.

Gastrin secretion was studied in 16 young anesthetized pigs weighing 14-26 kg. Test substances were infused (0.1 ml/min x 10-20 min) directly into the gastric antrum via a catheter in the right gastroepiploic artery. Samples were collected from a catheter in the right gastroepiploic vein and plasma gastrin was measured by radiommunoassay. The following results were observed: 1) basal gastrin in antral venous blood was 10-5 times that in peripheral blood (620+/-222 pg/ml vs. 41+/-10 pg/ml, 2) native bovine parathyroid hormone (PTH) and synthetic human 1-34 PTH (0.02-4U/min) produced rapid (within 10-30 min) and pronounced (approximately 10-fold) increases in gastrin release with no increase in plasma calcium and, in several animals, in the face of a falling plasma calcium concentration, 3) neither acute thyroidectomy nor infusion of porcine thyrocalcitonin (TCT), 0.5-2.5 U/min) consistently altered basal gastrin secretion (N=3-6), and 4) infusion of TCT (0.5 U/min)along with PTH (2U/min) significantly suppressed the 10-11-fold increase in gastrin release observed when PTH subsequently was infused alone in each pig (N=6). The results demonstrate that PTH can stimulate gastrin secretion in the pig and that TCT can suppress this effect.