display that their rods have a single-photon level of sensitivity similar to that of BIIE 0246 rods in other vertebrates. experiments the retinas were revealed for 3 min to 0.5 mg/ml collagenase and 0.33 BIIE 0246 mg/ml hyaluronidase to prevent clogging of pipettes by vitreous and extracellular matrix. To record from long photoreceptors (cones) we selected cells extending further from your retinal slice. The reactions of short photoreceptors (rods) were recorded by moving the electrode between cones or by searching for parts of the slice where the cones had been displaced during preparation. In Number 1 we display imply current reactions from the two kinds of photoreceptors to brief flashes of light. The short photoreceptors (A) experienced reactions resembling amphibian rods [for example 14]. The spectral level of sensitivity of the response (not demonstrated) was estimated by recording small-amplitude reactions to stimuli at selected wavelengths and dividing response amplitude by adobe flash intensity. The level of sensitivity measurements were then fitted to template curves [15] to estimate the peak of pigment absorbance which for the short photoreceptors was at about 520 nm [6 16 17 We consequently determine these cells as lamprey rods. The long photoreceptors (B) experienced reactions rising and decaying much more rapidly (notice difference in time level) standard of amphibian [18] and mouse cones [19] having a spectral level of sensitivity peaking at about 570 nm [6 16 We determine these cells as lamprey cones. In our limited sample all the cones experienced the same spectral level of sensitivity indicating a single spectral class of cone with this varieties of lamprey as previously reported [16]. Number 1 Current reactions of lamprey pole and BIIE 0246 cone photoreceptors to brief light stimuli. For both photoreceptor types response amplitude and period increase with increasing stimulus intensity. (A) Mean reactions of 11 rods to 20 ms 500 nm flashes given at … ART1 In Number 2 we have plotted the imply response amplitude (with SEM) like a function of adobe flash intensity for the cells of Number 1. The rods at 500 nm are of the order of 1 1.8 log models or 65 – 70 times more sensitive than the cones at 600 nm. We have fitted the reactions of each photoreceptor type to exponential saturation equations of the form = [1 ? exp(-is definitely response amplitude is the maximum value of is the adobe flash intensity and is a constant. The best-fitting ideals of in Number 2 were 10.1 pA and 1.5 × 10-2 photons-1 μm2 for rods and 10.4 pA and 2×10?4 photons-1 μm2 for cones. When ideals of and were estimated by fitted the response-intensity curves cell by cell we acquired 10.2 ± 0.8 pA and 1.3 ± 0.2 × 10-2 photons-1 μm2 for rods (SE n = 11) and 11.9 ± 2.4 pA and 1.6 ± 0.3 × 10-4 photons-1 μm2 for cones (n = 8). These measurements were made at wavelengths of activation that were somewhat different from our estimates of the wavelengths of maximal level of sensitivity of the two kinds of photoreceptors. For this reason we modified the sensitivities by a factor of 1 1.1 for rods and 1.24 for cones based on template curves for the photopigments [15] in order to estimate sensitivities in the λmax of the pigments. This gave imply values of of 1 1.4 × 10-2 photons-1 μm2 for rods and 2.0 × 10-4 photons-1 μm2 for cones providing mean values of the BIIE 0246 intensity required to give a half-maximal response (in the λmax of the pigments was therefore approximately 70. We conclude that rods are of the order of 70 occasions more sensitive than cones within the range of values recorded for additional vertebrate varieties [for example 19 21 BIIE 0246 Number 2 Level of sensitivity of pole and cone photoreceptors in lamprey. Current response amplitudes were plotted against their related adobe flash intensities for 11 rods (closed squares) and 8 cones (open squares). Same cells as with Figure 1. The data for both cell types … In Number 3 we compare the normalized waveforms of the reactions of rods and cones to flashes that for each photoreceptor type produced a response of about half-maximal amplitude. Because the cones were less sensitive than the rods the light intensity required to produce the cone response was of the order of 90 occasions brighter than the one used to stimulate the rods. The mean cone response experienced a much more quick rate of activation and time to peak at least in part the result of the brighter stimulus.