%0 Journal Article %T Steady-state osmotic modulation of cationic conductance in neurons of rat supraoptic nucleus. %+ Centre for Reserach in Neuroscience %A Oliet, Stéphane, H.R. %A Bourque, Charles, W. %< avec comité de lecture %@ 0002-9513 %J American Journal of Physiology %I American Physiological Society %V 265 %P R1475-9 %8 1993 %D 1993 %M 8285292 %Z Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]Journal articles %X 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. %G English %L inserm-00000081 %U https://inserm.hal.science/inserm-00000081 %~ INSERM