Effects of alkali metal cations on the labellar water receptor cell of the fleshfly,Boettcherisca peregrina

Dose-response relationships of the labellar water receptor cells of the fleshfly, Boettcherisca peregrina, in response to alkali-metal ions were studied electrophysiologically. When cation concentration was raised, the frequency of spikes from the water receptor cells was decreased. We analyzed the data under the assumption that channels on the water receptor membrane open when stimulated with water and are closed by alkali cations or nonelectrolytes. Dose-response relationships of the water receptor for NaCl, KCl and LiCl were analyzed using the Hill equation. The Hill coefficients and the activities of salts eliciting the half maximal response differed considerably among these salts. It is concluded that the effectiveness of salts on the inhibition of the water receptor cell differs among alkali metal ions, and that alkali cations interact cooperatively with the receptor membrane.