Rat cerebral cortical slice respiration in media of various osmolarities

Freshly separated immature (5-day-old) and mature (60-day-old) rat cerebral cortical tissue demonstrates a Na+-dependent respiratory component similar to that recently described in primary cultured astrocytes. This respiratory component, which is not coupled to oxidative phosphorylation, increases as the osmolarity is increased above 354 mOsm in media with NaCl as the osmotic agent. With decreasing osmolarity from 354 to 80 mOsm, this respiratory component decreases more in cortical tissue than in cultured astrocytes. We propose that the respiratory response of neurons to decreasing extracellular osmolarity may differ from that of astrocytes in situ.