The role of the parasympathetic system in the control of insulin release in the conscious calf.

1. The effect of atropine (0.2 mg/kg) on the release of insulin from the pancreas, in response to both exogenous and endogenous hyperglycaemia, has been investigated in conscious 2- to 5-week-old calves. 2 The rise in mean plasma insulin concentration in response to infusions of glucose, which raised the concentration of glucose in the plasma by about 4.0 mmol/l, was significantly depressed in calves with cut splanchnic nerves by prior administration of atropine. 3. The rise in plasma insulin concentration, which normally follows stimulation of the splanchnic nerves in the conscious calf (Bloom & Edwards, 1980), was almost completely suppressed by prior administration of atropine. 4. These findings are discussed in relation to those of other workers with other species. The results indicate that the parasympathetic innervation to the pancreas plays an important part in the control of insulin release in response to hyperglycaemia.