title: Ca2+ uptake by endoplasmic reticulum of renal cortex. II. Effects of uninephrectomy and parathyroidectomy.
abstract: Calcium uptake by the endoplasmic reticulum (ER) is important for cellular calcium homeostasis, yet its regulation in nonmuscle cells is poorly understood. We reported that Ca2+ uptake by a light fraction of canine renal cortical ER (LER) is stimulated by protein kinase C in vitro. Here we describe conditions in vivo that stimulate renal cortical LER Ca2+ uptake. Thirty minutes after contralateral nephrectomy in the dog, 45Ca2+ uptake into renal cortical LER was increased 42% above control LER. There was no difference in LER Ca2+ uptake 24 hours after uninephrectomy. Acute denervation did not reproduce the increase in LER 45Ca2+ uptake seen at 30 minutes after uninephrectomy, nor did prior thyroparathyroidectomy abolish it. Forty-eight hours after thyroparathyroidectomy, 45Ca2+ uptake activity into renal cortical LER was decreased approximately sevenfold. In a proximal tubular cell line (LLC-PK1), 30-minute incubation with 12-O-tetradecanoylphorbol-13-acetate doubled 45Ca2+ uptake into a nonmitochondrial pool. Pretreatment with epidermal growth factor halved ER Ca2+ uptake, whereas insulin-like growth factor and growth hormone, alone or in combination, had no effect. Our data suggest that Ca2+ uptake into renal cortical ER is stimulated acutely during compensatory renal growth, perhaps through protein kinase C, and is stimulated chronically by parathyroid hormone.
authors.affiliation: Department of Medicine, St. Louis University School of Medicine, John Cochran VA Medical Center, Missouri 63106.
authors.forename: D W
authors.initials: DW
authors.lastname: Moskowitz
authors.forename: K A
authors.initials: KA
authors.lastname: Hruska
mesh_terms: D000818:Animals; D002118:Calcium / Q000493:pharmacokinetics*; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D005260:Female; D006706:Homeostasis / Q000187:drug effects; D007672:Kidney Cortex / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D009392:Nephrectomy; D010281:Parathyroid Hormone / Q000502:physiology; D016105:Parathyroidectomy; D011493:Protein Kinase C / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium