In vitro release of pancreatic hormones following 99% pancreatectomy in the chicken.

In vitro assessment was made of the hormone-release capability of splenic pancreatic tissue 16 days after adult chickens had 99% of the pancreatic mass surgically removed. The objective of this study was to evaluate if the enlargement of the splenic lobe remnant after 99% pancreatectomy was attended by alterations in the responsivity of hormone release and, if so, were such changes reflective of all pancreatic hormones. After a 24-hr fast, splenic lobe tissue was obtained from young adult chickens on Postoperative Day 16, diced into 18-22 mg cubes, and incubated in vitro in media containing varying amounts of glucose with or without added somatostatin (SRIF). At 15-min intervals, the tissue cubes were transferred to fresh media and samples of each medium measured for insulin, glucagon, and APP. Viability of the tissue after 75 min was tested by tissue response to added 5 mM phenylalanine. The results obtained indicated that while total content of all four hormones (including SRIF) increased with tissue enlargement, the concentration of each decreased significantly except for SRIF, which remained at control levels. Further, the sensitivity of the B-cell in releasing insulin when confronted by a glucose challenge was not altered by previous pancreatectomy, while that of glucagon release from the A-cell was depressed. A-cell responsivity to SRIF does not appear to be adversely affected by previous 99% pancreatectomy. APP release was least affected by SRIF addition to the media, although depression by high glucose occurred. It is concluded that differential alterations occur in chicken pancreatic hormone-releasing cells as a result of 99% pancreatectomy. The efficacy in maintaining low, but still adequate, plasma I/G molar ratios (reported earlier) by the splenic remnant tissue either reflects a remarkable functional readjustment to surgical removal of 99% of the pancreatic mass in chickens or, alternatively, suggests the existence of extrapancreatic sources of insulin and glucagon, but not APP.