Relation between pancreatic growth and blood flow.

Male rats were treated with daily subcutaneous injections (3 micrograms/kg) of cholecystokinin octapeptide (CCK-OP), a synthetic CCK analogue, for 2, 4, 7, and 14 days, while control rats were injected with saline over the same intervals. Regional blood flows were measured with Sc46-labeled microspheres using the reference-organ method. Pancreatic wet and dry weights were determined in each treatment group. Total pancreatic DNA content was estimated with the diphenylamine reaction. Significant hyperplasia and increases in pancreatic wet weight occurred at 7 and 14 days, although hypertrophy was not evident in any of the treatment groups. No increases in small intestine wet weight or DNA content were evident in any treatment group. CCK-OP treatment induced a significant pancreatic hyperemia at 2 and 4 days of treatment. Pancreatic blood flow at 7 and 14 days was not different from control when expressed per unit tissue weight. The hyperemia seen at 2 and 4 days was not due to either a direct vascular effect of CCK-OP or an increase in pancreatic exocrine secretion. The hyperemia is therefore due to the growth stimulus and may be related to vasodilator metabolite accumulation during pancreatic tissue proliferation.