EXISTENCE OF MULTIPLE RECEPTORS IN SINGLE NEURONS - RESPONSES OF SINGLE BULLFROG OLFACTORY NEURONS TO MANY CAMP-DEPENDENT AND INDEPENDENT ODORANTS

The responses of single bullfrog olfactory neurons to various odorants were measured with the whole-cell patch clamp which offers direct inf ormation on cellular events and with the ciliary recording technique t o obtain stable quantitative data from many neurons. A large portion o f single olfactory neurons (about 64% and 79% in the whole-cell record ing and in the ciliary recording, respectively) responded to many odor ants with quite diverse molecular structures, including both odorants previously indicated to be cAMP-dependent (increasing) and independent odorants. One odorant elicited a response in many cells; e.g. hedione and citralva elicited the response in 100% and 92% of total neurons e xamined with the ciliary recording technique. To confirm that a single neuron carries different receptors or transduction pathways, the cros s-adaptation technique was applied to single neurons. Application of h edione to a single neuron after desensitization of the current in resp onse to lyral or citralva induced an inward current with a similar mag nitude to that applied alone. It was suggested that most single olfact ory neurons carry multiple receptors and at least dual transduction pa thways.