Water response of the frog olfactory epithelium as observed from the olfactory bulb.

The water response elicited by application of distilled water on the olfactory epithelium was recorded extracellularly from single olfactory bulb neurones. Characteristics of the water response in the frog olfactory epithelium were examined in comparison with those of the water response in the gustatory and palatal organs. 1. Effects of various electrolyte solutions on the generation of the water response were studied by dripping distilled water on the olfactory epithelium after adaptation to each of these electrolyte solutions. Number of the olfactory bulb cells responding to distilled water increased with increasing the charge of the adapting cations and also with decreasing the size of the cations with a few exceptions. 2. Magnitude of the 'water response' increased with decreasing concentration of salt in the solution which was dripped after adaptation to the isotonic solution of the same salt. 3. The water response was effectively depressed by an electrolyte solution but not by a non-electrolyte solution. An electrolyte also depressed effectively the water response which was produced after adaptation to an organic salt solution. 4. The water response was blocked by treatment of the olfactory epithelium with the uranyl ions which had high affinity for phospholipids. A tentative hypothesis on the generating mechanism of the water response in the frog olfactory epithelium is presented on the basis of the present experimental results and the water responses of the gustatory and palatal organs so far reported.