ABSTRACT
The effects of different dilutions of Locke solution on the electrical activity of the isolated pedal ganglion of the slug can be reproduced by adding different concentrations of glucose or mannitol to a given concentration of Locke.
This indicates that certain cells in the pedal ganglion are sensitive to the osmotic pressure of the solution and not its ionic concentration.
The preparation is sensitive to slow changes in the concentration of the bathing medium. The cells increased their activity when the bathing solution was slowly changed from 0-7 Locke to o-6 Locke, the change taking 43 min. This corresponds approximately to a change of 1 % of the body fluid concentration over 4 min. Such rates of change are found in the normal intact animal.
The sensitivity of the preparation compares well with that of the mammalian osmoreceptors.
