title: Hormone-mediated Ca2+ transients in isolated renal cortical thick ascending limb cells.
abstract: Peptide hormones control salt reabsorption in cortical thick ascending limb (cTAL) cells of the loop of Henle. These agonists act, in part, through alterations on intracellular Ca2+ ([Ca2+]i). Primary cell cultures were prepared from porcine kidneys using a double antibody technique (goat antihuman Tamm-Horsfall and rabbit antigoat IgG antibodies). [Ca2+]i was determined in single cells with fluorescent techniques using fura-2. Parathyroid hormone (PTH) and arginine vasopressin (AVP) transiently increased [Ca2+]i in a dose-dependent manner. [Ca2+]i maximally increased from 85 +/- 5 nmol/l to 608 +/- 99 nmol/l with PTH, 10(-6) M, and to 766 +/- 162 nmol/l with AVP, 10(-7) M. The increment in [Ca2+]i by both hormones was by intracellular Ca2+ release and entry through plasma membrane Ca2+ channels. 8-Bromo-adenosine-3',5'-cyclic monophosphate (8-BrcAMP), 10(-4) M, increased [Ca2+]i (basal 83 +/- 3 to 427 +/- 121 nmol/l) but only from internal sources as nifedipine (10 mumol), ([Ca2+]i changes: 86 +/- 4 to 390 +/- 29 nmol/l) and removal of bath Ca/+o, ([Ca2+]i changes: 84 +/- 6 to 517 +/- 142 nmol/l), were without effect on agonist-induced [Ca2+]i. Thapsigargin, 1.5 mumol, completely abolished the AVP- and cyclic adenosine monophosphate-(cAMP)-induced Ca2+ transients, and partially inhibited PTH-mediated Ca2+ transients by about 50%. Pretreatment with 8-BrcAMP inhibited the PTH and AVP responses likely through depletion of cAMP-sensitive Ca2+ stores. Activation of protein kinase C (PKC) with phorbol esters inhibited PTH and AVP responses and 8-BrcAMP-induced [Ca2+]i transients.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University Hospital--UBC Site, University of British Columbia, Vancouver, Canada.
authors.forename: L J
authors.initials: LJ
authors.lastname: Dai
authors.forename: G A
authors.initials: GA
authors.lastname: Quamme
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002469:Cell Separation; D000242:Cyclic AMP / Q000494:pharmacology; D004789:Enzyme Activation; D006728:Hormones / Q000502:physiology*; D007672:Kidney Cortex; D008138:Loop of Henle / Q000166:cytology / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine
chemical_list: D006728:Hormones; D010281:Parathyroid Hormone; D001127:Arginine Vasopressin; D000242:Cyclic AMP; D011493:Protein Kinase C; D002118:Calcium