Whole cell recording from lobster olfactory receptor cells: responses to current and odor stimulation

1. The basic electrical properties of olfactory (antennule) receptor cells were studied in an in situ preparation of the spiny lobster using whole cell patch-clamp recording. 2. The current-voltage relationship of the cells was linear for membrane potentials between -150 and -40 mV and rectified at more positive membrane potentials. The input resistance at rest averaged 508 M omega. The cells displayed two time constants, with mean values of 29.8 and 8.2 ms. 3. Depolarizing current steps elicited fast, overshooting action potentials at a mean threshold of -32 mV from an imposed resting membrane potential of -65 mV. The action potentials were tetrodotoxin (TTX) and tetraethylammonium (TEA) sensitive, suggesting they are typical sodium/potassium action potentials. 4. Odor stimulation evoked slow, dose-dependent, depolarizing receptor potentials up to 50 mV in amplitude. In approximately 30% of cells tested, these led to repetitive spiking when the cells were depolarized beyond -45 to -30 mV. The amplitude of the receptor potential was graded as a linear function of the logarithm of the odor concentration. 5. The amplitude of the receptor potential varied linearly with the membrane potential between -70 and -30 mV. Extrapolated reversal potentials appeared to be normally distributed around a mean value of -3.6 mV. 6. The results collectively indicate that lobster olfactory receptor cells have electrical properties similar to, but not necessarily identical with, those currently envisaged for olfactory receptor cells in other species.