Action of an Osmoreceptor

Actin filaments in brain osmoreceptors detect changes in solute concentration in the interstitial fluid when the cell membrane expands or contracts. Changes in cell volume cause changes in the membrane potential, which serve as the signal for osmometric thirst. (b) Opposite effects were seen when cell volume was reduced by a hypertonic solution and then increased by applying pressure through the micropipette. (Adapted from Zhang, Z., Kindrat, A. N., Sharif-Naeini, R., and Bourque, C. W. Journal of Neuroscience, 2007, 27, 4008–4013.)