The circulating hormonal milieu of the endocrine pancreas in healthy individuals, organ donors, and the isolated perfused human pancreas

Although basal circulating levels of individual islet cell hormones have be en measured, few studies compared the molar ratios of the major hormones se creted by the endocrine pancreas. This study examined the basal levels of f our major islet hormones: insulin, C-peptide (C-P), glucagon (G), and pancr eatic polypeptide (PP) in normal subjects, in organ donors with brain death , and in the isolated perfused human pancreas. Basal blood samples were tak en from normal, fasted control subjects (NCs). Pancreata were obtained from 17 organ donors (ODs) with donor portal vein (DPV) and radial arterial (DR A) blood samples taken before organ procurement. Single-pass perfusion was performed on the procured pancreata, and after rewarming and equilibration, basal samples were collected from the splenic vein (SV) for 30 min. Radioi mmunoassays of insulin, C-P, G, and PP were performed on all samples, and b asal levels of all hormones were expressed as a common unit, femtomoles per milliliter. The data suggest that in the basal state, these four major isl et hormones circulate in a relatively constant molar ratio. The ratio of th e hormones is altered in brain death and with in vitro perfusion of the pan creas. The isolated perfused human pancreas secretes a relatively constant molar ratio of these hormones; however, this ratio is markedly different fr om the circulating ratio seen in either the NC group or the OD group. We co nclude that a relatively constant hormonal milieu is secreted from the norm al endocrine pancreas, and this hormonal milieu is altered after brain deat h and with isolation and perfusion of the human pancreas.