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Regulatory mechanism of parathyroid hormone-dependent Ca transport in connecting tubule.

Research Project

Project/Area Number 05670054
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field General physiology
Research InstitutionJichi Medical School

Principal Investigator

TANIGUCHI Junichi  Faculty of Medicine, Jichi Medical School Assistant, 医学部, 講師 (90179838)

Project Period (FY) 1993 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Keywordsconneting tubule / Ca excretion / parathyroid hormone / nonselective cation channel / stretch-activated channel / flow dependence / gadolinium / dihydropyridine / Ca排泄調節 / 圧依存性 / Ca排泄調整 / fura2 / Ca流入 / Ca^<2+>代謝 / Ca^<2+>排泄 / cAMP / 管腔側膜
Research Abstract

To characterize parathyroid hormone (PTH) -dependent luminal Ca^<2+> transport in rabbit connecting tubule (CNT), I examined the effects of luminal pressure on this transport. Cytoplasmic Ca^<2+> concentraion ([Ca^<2+>]_i) in fura 2-loaded CNT perfused in vitro was elevated by 42<plus-minus>11nM by increasing luminal pressure (0.2 to 1.2KPa).Basolateral 10nM PTH accelerated the response to 101<plus-minus>30nM.The response was augmented from 36<plus-minus>16nM to 84<plus-minus>26nM by 0.1mM chlorphenyl-thio-cAMP (CPT-cAMP). Under steady perfusion pressure at 1.2KPa, 10nM PTH increased [Ca^<2+>]i by 31<plus-minus>7nM,whereas it did by 6([SY.+-.[)2nM at 0.2KPa. The pressure dependent increase of [Ca^<2+>]_i was abolished by removing luminal Ca^<2+> in the presence of 10nM PTH,and was not affected by luminal 0.1 or 10 mu M nicardipine. Both 100 mu M nifedipine and benijipine suppressed by 24<plus-minus>6% and by 30<plus-minus>11% of [Ca^<2+>]i increased by 50nM PTH,respectively, but 10 mu M Gd^<3+> did by 90<plus-minus>19%. 10nM PTH hyperpolarized transmural voltage, followed by depolarization. Luminal Gd^<3+> (10 mu M) reduced only depolarization by 60<plus-minus>19%. Cell-attached patch clamp studies on the apical membrane of everted CNT using pipette filled with either 200mM CaCl_2 or 140mM NaCl revealed channel activities (42<plus-minus>2pS or 173<plus-minus>7pS,respectively). Negative pressure (-4.9KPa) applied to patch pipette augmented its mean number of open channels from 0.005<plus-minus>0.001 to 0.022<plus-minus>0.005 in the Ca^<2+>-filled pipette, and was further accelerated to 0.085<plus-minus>0.014 by 0.1mM CPT-cAMP.In the Na^+-filled pipette, similar results were obtained, and CPT-cAMP did not activate unstretch channels. These results revealed that stretch-activated nonselective cation channel is a dominant route of Ca^<2+> transport via luminal membrane of rabbit CNT and that PTH stimulates it in the presence of luminal pressure or fluid flow.

Report

(4 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • 1993 Annual Research Report
  • Research Products

    (5 results)

All Other

All Publications (5 results)

  • [Publications] Makoto Suzuki: "A Ca^<2+> channel in renal epithelial introduced by parathyroid hormone." Miner Electrolyte Metab.21. 35-39 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Makoto Suzuki and Junichi Taniguchi.: "A Ca^<2+> channel in renal epithelial introduced by parathyroid hormone." Miner Electrolyte Metab.21. 35-39 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Makoto Suzuki: "A Ca^<2+> channel in renal epithelial introduced by parathyroid hormone." Miner Electrolyte Metab. 21. 35-39 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] Junichi Taniguchi: "Pressure-and parathyroid-hormone-dependent Ca^<2+> transport in rabbit connecting tubule:Role of the stretch-activated nonselective cation channel." J.Membr.Biol.140. 123-132 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 今井,正: "遠位側ネフロンの細胞内情報伝達と利尿薬" nanoGIGA. 2. 103-110 (1993)

    • Related Report
      1993 Annual Research Report

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Published: 1993-04-01   Modified: 2016-04-21  

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