Involvement and source of calcium in volume regulatory decrease of collapsed proximal convoluted tubule
| Autor: | Raynald Laprade, J. S. Beck, G. Giebisch, Sylvie Breton, J. Cardinal |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Osmotic shock
Physiology chemistry.chemical_element Calcium Kidney Tubules Proximal chemistry.chemical_compound Gallic Acid Extracellular Animals Lagomorpha biology Chemistry Shock Intracellular Membranes Calcium Channel Blockers biology.organism_classification Molecular biology Electrophysiology Hypotonic Shock EGTA Convoluted tubule Hypotonic Solutions Biochemistry Rabbits Extracellular Space Intracellular |
| Zdroj: | American Journal of Physiology-Renal Physiology. 263:F656-F664 |
| ISSN: | 1522-1466 1931-857X |
| DOI: | 10.1152/ajprenal.1992.263.4.f656 |
| Popis: | We examined the role of Ca2+ in the volume regulatory decrease (VRD) of rabbit collapsed proximal tubules. Reduction of bath osmolality by 125 mosmol/kgH2O led to an initial cell swelling of 62.3 +/- 7.5% followed by a partial regulatory phase bringing cell volume to a value of 13.3 +/- 2.9% above control (n = 5). This swelling was accompanied by a transient intracellular Ca2+ ([Ca2+]i) increase from 174 +/- 33 to 306 +/- 67 nM (P < 0.05, n = 8). In the same condition, but in absence of extracellular Ca2+ ([Ca2+]e) [1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)], VRD following hypotonic shock was identical to that observed in presence of [Ca2+]e (n = 5), and [Ca2+]i increased transiently from 136 +/- 29 to 161 +/- 31 nM (P < 0.05, n = 5). Addition of 100 microM 8-(N,N-dimethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8), an agent known to inhibit Ca2+ release from intracellular stores, did not affect the initial cell swelling (63.4 +/- 4.2%), and VRD occurred to the same extent (25.0 +/- 7.1%, n = 4), although at a lower rate. In these conditions, [Ca2+]i, which was 113 +/- 30 nM in the isotonic solution, decreased progressively to 81 +/- 20 nM over the 5-min hypotonic period (n = 5). Mere preincubation with 100 microM TMB-8 before hypotonic shock led to a VRD identical to that observed in presence of Ca2+ and absence of TMB-8 while still blocking the Ca2+ release, with cell Ca2+ decreasing progressively from 179 +/- 32 to 87 +/- 21 nM (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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