The hyperglycaemic response to stimulation of the hepatic sympathetic innervation in adrenalectomized cats and dogs.

1. The extent to which the hyperglaemic and glycogenolytic responses to splanchnic nerve stimulation depend upon the integrity of the hepatic innervation has been investigated in adrenalectomized dogs and cats.2. In both species maximal stimulation of the hepatic nerves (20 c/s) produced changes in plasma glucose concentration comparable to those which have been found to occur in response to bilateral splanchnic nerve stimulation at the same frequency. Furthermore, the hyperglycaemic response to splanchnic nerve stimulation was very substantially reduced by section of the hepatic nerves, whereas the associated changes in haematocrit and mean aortic blood pressure were not significantly altered.3. Comparison of the changes in plasma glucose concentration in response to splanchnic or hepatic nerve stimulation at relatively low frequencies (1.0-2.0 c/s) showed that stimulation of either nerve produced closely similar responses in adrenalectomized animals of both species.4. In adrenalectomized dogs maximal stimulation of the hepatic nerves (20 c/s) for shorter periods (30 sec) caused a significant rise in plasma glucose concentration whereas total occlusion of the portal vein for the same period in the same animals produced no statistically significant hyperglycaemic effect.5. Maximal stimulation of the hepatic nerves (20 c/s) caused a rapid rise in plasma glucose concentration in hypoglycaemic adrenalectomized cats pretreated with a large dose of insulin (4 u./kg body wt.).6. It is concluded that the hyperglycaemic response to stimulation of the peripheral ends of the splanchnic nerves in adrenalectomized dogs and cats is directly dependent upon activation of sympathetic efferent fibres to the liver.