PANCREATIC ENDOCRINE FUNCTION IN RECIPIENTS OF SEGMENTAL AND WHOLE PANCREAS TRANSPLANTATION

To determine potential abnormalities in beta-cell function after pancr eas transplantation, the secretory capacity of the pancreatic grafts w as assessed by measuring the glucose-potentiating effect on arginine-i nduced insulin secretion in recipients of cadaveric segmental (SPx; n = 8) and whole organ pancreas grafts (WPx; n = 6) and compared to that in nondiabetic kidney transplant recipients (Kx; n = 6) and normal co ntrols (Ns; n = 7). alpha-Cell adaptation to increasing hyperglycemia and the glucagon response to arginine stimulation were also studied. T he secretory capacity of the beta-cell to arginine-induced (5 g L-argi nine) insulin secretion was measured at fasting plasma glucose and 15 and 30 mmol/L glucose. Insulin secretion was evaluated by the calculat ion of insulin secretion rates. Insulin sensitivity was markedly reduc ed in all three transplanted groups compared to that in normal subject s (P < 0.05). The prestimulation insulin secretion rate and maximal in sulin secretion rate in response to hyperglycemia and arginine were si gnificantly lower in SPx than in WPx, Kx, or Ns (P < 0.05). The increm ental amount of insulin secreted in response to arginine was reduced b y 40-70% in SPx depending on glycemia compared to that in all other gr oups (P < 0.05), among which there were no statistical differences. Bo th SPx and WPx demonstrated suppression of glucagon release in respons e to graded hyper glycemia, but failure to adequately suppress arginin e-induced glucagon release. In conclusion, recipients of cadaveric seg mental pancreas grafts display a markedly reduced maximal insulin secr etory reserve capacity. This impairment was primarily due to an insuff icient beta-cell mass. Taking the concomitant insulin resistance into account, recipients of a cadaver whole organ pancreas graft had an imp aired insulin secretory reserve capacity as well.