The effect of intraportal and intravenous glucose infusion and an intravenous glucose tolerance test on insulin and glucagon levels in conscious cats with normal and chronically phenol-denervated livers.
Cats were prepared with chronically implanted catheters in the portal and femoral vein for administration of glucose. A femoral arterial catheter was used for blood sampling. After at least 5 days following the implantations, cats received an infusion of 3 mg/kg/min into the portal vein and the insulin and glucagon responses were compared with a similar infusion into the femoral vein. The hypothesis predicted that glucose receptors in the liver would result in greater pancreatic hormonal responses than would be seen with the femoral infusions of glucose. This did not occur. There was no statistically significant difference between the rise in insulin and the decrease in glucagon elicited by the glucose infusion into the two alternate infusion sites. A sham-denervated series showed similar responses. A group of cats that underwent hepatic denervation using topical phenol application to the hepatic plexus near the hilum of the liver was tested. The responses of the denervated group were similar to those for the control and sham-operated groups, confirming that hepatic glucose receptors do not serve as an afferent limb of a hepato-pancreatic reflex controlling insulin and glucagon release in conscious cats. In all experiments, a bolus of glucose (500 mg) was injected i.v. to represent a tolerance test. The responses of blood glucose levels, pancreatic insulin and glucagon and recovery from the stimulus were similar in all groups which suggests that hepatic nerves are not essential for a normal hepatic response to intravenously infused glucose. It is suggested, however, that hepatic nerves may be important in producing normal hepatic responses to oral glucose loads.
D000818:Animals; D002415:Cats; D003714:Denervation; D005934:Glucagon / Q000097:blood*; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D007263:Infusions, Parenteral; D007328:Insulin / Q000097:blood*; D008099:Liver / Q000294:innervation*; D019800:Phenol; D010636:Phenols; D011169:Portal Vein; D011956:Receptors, Cell Surface / Q000502:physiology*
D007328:Insulin; D010636:Phenols; D011956:Receptors, Cell Surface; C027786:glucose receptor; D019800:Phenol; D005934:Glucagon; D005947:Glucose