Osmoreceptors in the central nervous system.

Charles W. Bourque and, Stéphane H. R. Oliet
Annu. Rev. Physiol.. 1997-10-01; 59(1): 601-619
DOI: 10.1146/annurev.physiol.59.1.601

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Osmoreceptors regulate sodium and water balance in a manner that maintains the
osmotic pressure of the extracellular fluid (ECF) near an ideal set point. In
rats, the concerted release of oxytocin and vasopressin, which is determined by
the firing rate of magnocellular neurosecretory cells (MNCs), plays a key role in
osmoregulation through the effects of natriuresis and diuresis. Changes in
excitatory synaptic drive, derived from osmosensitive neurons in the organum
vasculosum lamina terminalis (OVLT), combine with endogenously generated
osmoreceptor potentials to modulate the firing rate of MNCs. The cellular basis
for osmoreceptor potentials has been characterized using patch-clamp recordings
and morphometric analysis in MNCs isolated from the supraoptic nucleus of the
adult rat. In these cells, stretch-inactivated cationic channels transduce
osmotically evoked changes in cell volume into functionally relevant changes in
membrane potential. The experimental details of these mechanisms are reviewed in
their physiological context.


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