Comparative effects of secretin (SEC) and cholecystokinin-octapeptide (CCK-8) on pancreatic microcirculation

Using epifluorescent microscopy, we investigated the dynamic changes in pancreatic microcirculationin vivo after bolus administration of secretin (SEC) (0.1–10.0 µg/100 g body wt) and cholecystokinin-octapeptide (CCK-8) (0.005–1.2 µg/100 g body wt) in pentobarbital-anesthetized rats. Pancreatic capillary red cell velocity as a monitor for pancreatic capillary blood flow was measured in 1-min intervals from 2 min prior to 8 min following bolus infusion of SEC or CCK-8. Physiological concentrations of SEC did not increase pancreatic capillary blood flow. However, pharmacological SEC concentrations induced a dose-dependent increase in pancreatic capillary blood flow (to 162±19% of baseline;P<0.05), due to an increase in blood flow velocity (to 153±18% of baseline;P<0.05). In contrast, bolus administration of physiological CCK-8 concentrations, which have been proven to stimulate enzyme secretion, induced a transient and dose-dependent increase in pancreatic capillary blood flow (to 235±24% of baseline;P<0.05), due to an increase in blood flow velocity (to 184±13% of baseline;P<0.05) and capillary diameters (+0.63 ± 0.15 µm;P<0.05).