Effect of intact parathyroid hormone on hepatic glucose release in the dog.
The liver has been shown to remove parathyroid hormone (PTH) from its arterial circulation by a mechanism that is selective for the intact form of the peptide (PTH 1-84). The present studies demonstrate that PTH has biologic effects on the liver in vivo. Bovine PTH 1-84 stimulated hepatic glucose release in dogs with indwelling hepatic vein catheters from basal values of 31+/-8 to 68+/-9 mg/min per kg after bolus injections of PTH. The effect on hepatic glucose release was apparent by 5 min and persisted for the 80 min of observation. The NH(2)-terminal PTH fragment (syn b-PTH 1-34) had no effect. Bovine PTH 1-84 administered in doses designed to produce circulating levels of immunoreactive PTH similar to the endogenous levels observed in uremic dogs also increased the incorporation of (14)C from infused [(14)C]alanine into glucose, and increased estimated hepatic uptake of both chemical and [(14)C]alanine, while increasing hepatic glucose release. Thus, administration of "physiologic levels" of b-PTH 1-84 stimulated hepatic glucose release in part through increased gluconeogenesis in vivo, whereas syn b-PTH 1-34 had no demonstrable effect. Circulating levels of insulin rose after PTH administration, an increase which presumably represents a secondary response to the rise in glucose release. These results suggest that the liver is a target organ of PTH, and that PTH might potentially alter carbohydrate metabolism during hypersecretion. They also suggest that hepatic uptake of PTH may be related in part to production of a specific biologic effect rather than just simple peptide degradation.
D000818:Animals; D001786:Blood Glucose; D004285:Dogs; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D008099:Liver / Q000098:blood supply / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000138:chemical synthesis / Q000494:pharmacology*; D012039:Regional Blood Flow
D001786:Blood Glucose; D007328:Insulin; D010281:Parathyroid Hormone; D005934:Glucagon; D005947:Glucose