title: High glucose stimulates Ca2+ uptake via cAMP and PLC/PKC pathways in primary cultured renal proximal tubule cells.
abstract: Alteration of [Ca2+]i by hyperglycemia is implicated in the pathogenesis of diabetic nephropathy. However, the effect of high glucose on Ca2+ regulation in proximal tubule cells is not known. Thus, we examined the mechanisms by which high glucose regulates Ca2+ uptake in primary cultured rabbit renal proximal tubule cells. Glucose increased the Ca2+ uptake in a time- and dose-dependent manner. A stimulatory effect of high glucose on Ca2+ uptake is predominantly observed using 25 mM glucose (high glucose) after 1 h, while 25 mM glucose did not affect cell viability and lactate dehydrogenase release. However, 25 mM mannitol and L-glucose did not affect Ca2+ uptake as compared with controls. Nifedipine and methoxyverapamil (L-type Ca2+ channel blockers) blocked high-glucose-induced stimulation of Ca2+ uptake. High-glucose-induced stimulation of Ca2+ uptake was blocked by pertussis toxin, SQ-22536 (adenylate cyclase inhibitor), myristoylated amide 14-22 (protein kinase A inhibitor), neomycin and U-73122 (phospholipase C inhibitors), and staurosporine and bisindolylmaleimide I (protein kinase C inhibitors). In addition, KN-62 (a Ca2+/calmodulin-dependent protein kinase II inhibitor) and W-7 (a Ca2+/calmodulin antagonist) blocked high-glucose-induced stimulation of Ca2+ uptake. In conclusion, high glucose stimulates the Ca2+ uptake through L-type Ca2+ channels via G-protein-coupled adenylate cyclase/cAMP and phospholipase C/protein kinase C pathways.
authors.affiliation: Department of Veterinary Physiology, College of Veterinary Medicine, Hormone Research Center, Chonnam National University, Kwangju, Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: H J
authors.initials: HJ
authors.lastname: Choi
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: I S
authors.initials: IS
authors.lastname: Yang
authors.forename: H J
authors.initials: HJ
authors.lastname: Han
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003928:Diabetic Nephropathies / Q000209:etiology; D005947:Glucose / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D011817:Rabbits; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D005947:Glucose; D002118:Calcium