title: Impaired potassium-induced insulin secretion in chronic renal failure.
abstract: Extrarenal disposal of potassium load is impaired in chronic renal failure (CRF). This has been attributed to excess PTH since extrarenal disposition of potassium is normal in CRF-PTX animals. Insulin augments potassium entry into cells and hyperkalemia stimulates insulin secretion. Since glucose-induced insulin secretion is impaired in CRF and normal in CRF-PTX, it is possible that K(+)-induced insulin secretion is also impaired in CRF due to excess PTH. Such a defect would contribute to the abnormality in extrarenal disposal of potassium in CRF. We examined K(+)-induced insulin secretion, cytosolic calcium ([Ca2+]i) and the changes in [Ca2+]i in response to 20 mM KCl of islets from normal, CRF, and CRF-PTX rats; and normal and CRF animals treated with verapamil (normal-V and CRF-V). K(+)-induced insulin secretion by islets isolated from CRF rats was significantly (P less than 0.01) lower than that from normal, CRF-PTX, CRF-V and normal-V rats. Basal level of [Ca2+]i in islets of CRF rats was significantly (P less than 0.01) higher than in islets of the other four groups of animals. The calcium signal (delta [Ca2+]i) and the delta [Ca2+]i/basal [Ca2+]i ratio in response to 20 mM KCl observed in islets from CRF rats were significantly lower than in the other four groups of animals.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Southern California School of Medicine, Los Angeles.
authors.forename: G Z
authors.initials: GZ
authors.lastname: Fadda
authors.forename: P
authors.initials: P
authors.lastname: Thanakitcharu
authors.forename: R
authors.initials: R
authors.lastname: Comunale
authors.forename: L G
authors.initials: LG
authors.lastname: Lipson
authors.forename: S G
authors.initials: SG
authors.lastname: Massry
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood; D003404:Creatinine / Q000097:blood; D006962:Hyperparathyroidism, Secondary / Q000209:etiology / Q000503:physiopathology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D008297:Male; D010281:Parathyroid Hormone / Q000378:metabolism; D010758:Phosphorus / Q000097:blood; D011188:Potassium / Q000097:blood / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects; D015398:Signal Transduction
chemical_list: D007328:Insulin; D010281:Parathyroid Hormone; D010758:Phosphorus; D003404:Creatinine; D011188:Potassium; D002118:Calcium