The effect of adrenaline and noradrenaline on the blood flow, electrical conductance and external secretion of the pancreas.

1. Adrenaline and noradrenaline cause a biphasic change in the transverse electrical conductance across the cat pancreas. After a latent period of from 5 to 30 sec a phase of decreased conductance lasting about 30 sec occurs which gives way to a phase of increased conductance lasting from 5 to 8 min.2. Coincidentally with the phase of decreased conductance, vasoconstriction and a reduction in blood flow occurs and an increased blood flow with the phase of increased conductance. The blood flow and conductance records run a parallel time course.3. Weight for weight adrenaline produces changes of greater magnitude than noradrenaline.4. The phase of decreased conductance and blood flow was abolished by an alpha-receptor blocking agent and the phase of increased conductance and blood flow by a combination of alpha- and beta-receptor blocking agents.5. Inhibition of the volume rate of secretion coincident with the phase of decreased conductance followed rapid intravenous injection of adrenaline or noradrenaline. During the phase of increased conductance secretion either returned to control values or was transiently augmented.6. Inhibition of secretion occurred after alpha-receptor blockade in the absence of vasoconstriction, suggesting that the catecholamines have a direct action on the cell.7. beta-receptor blockade increased the effectiveness of adrenaline to inhibit pancreatic secretion. When the effects of the catecholamines on secretion were tested, secretion was always induced by secretin.