The glycogenolytic response to stimulation of the splanchnic nerves in adrenalectomized calves, sheep, dogs, cats and pigs

Abstract

1. The effects of stimulation of the peripheral ends of one or both splanchnic nerves have been investigated in calves, sheep, dogs, cats and pigs after removal of both adrenal glands.2. Stimulation of both splanchnic nerves produced comparable hyperglycaemic and glycogenolytic effects in sheep, dogs and cats; the mean liver glycogen concentration was reduced by between 7.0 and 10.5 mg/g, five min after stimulation was discontinued, at which time the mean plasma glucose concentration had risen by between 126 and 137 mg/100 ml.3. In five 3-5 week-old calves which were tested under identical conditions the mean liver glycogen concentration was reduced by 13.3 +/- 1.9 mg/g and the plasma glucose concentration raised by 216 +/- 1.9 mg/100 ml., 5 min after stimulation was terminated.4. In pigs, stimulation of both splanchnic nerves invariably produced a rise in the plasma glucose concentration, even when the concentration of glycogen in the liver was less than 5 mg/g before stimulation. The response was, nevertheless, considerably smaller in these animals than in any of the other species investigated.5. Splanchnic nerve stimulation also caused a rise in mean aortic blood pressure and blood haematocrit during the period of stimulation; changes of approximately the same order of magnitude were encountered in all five species.6. Dogs were found to resemble calves in that the hyperglycaemic response to stimulation of a single splanchnic nerve did not differ significantly from that obtained when both were stimulated simultaneously; furthermore, either nerve was found to be equally effective.7. In cats the change in plasma glucose concentration in response to stimulation of a single splanchnic nerve was always less than that which occurred in response to bilateral stimulation although comparable changes in blood haematocrit occurred in both groups of animals.8. It is concluded that stimulation of the splanchnic nerves causes break-down of glycogen in the livers of various unrelated species of adult animals but that the magnitude of the hyperglycaemic response in the young calf provides further evidence of the importance of the sympathetic system in the control of metabolism in the young animal.