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Steady-state osmotic modulation of cationic conductance in neurons of rat supraoptic nucleus.

Abstract : Whole cell patch-clamp recordings were obtained from isolated rat supraoptic nucleus magnocellular neurosecretory cells (MNCs). Under current clamping, hyperosmolality produced by the addition of 10-30 mM mannitol depolarized each of 25 cells tested. In contrast, reducing fluid osmolality from 295 to 265 mosmol/kgH2O had the reverse effect, hyperpolarizing 18 of 21 MNCs. Voltage-clamp recordings in 43 cells revealed that the effects of hypo- and hyperosmolality, respectively, were caused by decreases and increases in a nonselective cation conductance reversing near -41 mV. Current-voltage analysis in Na(+)-free solution revealed that the reversal potentials of currents elicited by increases and decreases in osmolality both shifted to a value near -90 mV, suggesting that a single ionic conductance is modulated by these stimuli. The relation between cationic conductance and osmolality was specific, sensitive (+2.14%.mosmol-1.kgH2O-1), and well-fit by linear regression (r = 0.96; n = 22 cells) between 275 and 325 mosmol/kgH2O. These results indicate that MNCs express a depolarizing current that is active under steady-state conditions and that the up- or downregulation of this current contributes to the excitation or inhibition of these cells upon acute exposure to hypo- or hyperosmolar conditions.
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https://www.hal.inserm.fr/inserm-00000081
Contributor : Stéphane Oliet <>
Submitted on : Wednesday, March 29, 2006 - 12:22:42 PM
Last modification on : Thursday, June 18, 2020 - 12:32:04 PM

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  • HAL Id : inserm-00000081, version 1
  • PUBMED : 8285292

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Stéphane Oliet, Charles Bourque. Steady-state osmotic modulation of cationic conductance in neurons of rat supraoptic nucleus.. American Journal of Physiology, American Physiological Society, 1993, 265, pp.R1475-9. ⟨inserm-00000081⟩

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