Figure 1.
Current responses induced by photorelease of 8-Br-cAMP as a function of flash intensity. (A) 50 μM caged 8-Br-cAMP diffused into the cell from the patch pipette and flashes of increasing intensity and identical duration were applied to the ciliary region. The arrow indicates the time of application of light flashes of various relative intensities: 0.1, 0.32, 0.5, and 1. Whole-cell current responses were measured at the holding potential of −50 mV. (B) Peak currents from the cell in A were plotted as a function of the relative light intensity, F. The continuous line was the best fit of the Hill Eq. 1 to the data with the following values: Imax = 226 pA, F1/2 = 0.41, and n = 5.4. (C) Collected results from nine different olfactory sensory neurons. Each symbol represents a different cell. Both axes are normalized values. Normalized peak currents in each cell (I/Imax) were plotted versus the logarithm of the relative intensity normalized to the F1/2 value (F/F1/2) for each cell. The continuous line was the best fit of Eq. 1 to the collected data with n = 3.3. Values of F1/2 ranged from 0.10 to 0.47, n from 3 to 5.4, and Imax from −160 to −1200 pA.