Mice were reared in 12?h cyclic light, dark-adapted overnight before recordings, and euthanized by CO2 narcosis followed by decapitation. All mice were between one and six months of age when used for experiments. GCAPs?/? mice ( 13) were obtained from Dr. Jeannie Chen (University of Southern California, Los Angeles, CA) and maintained as an inbred strain in our vivarium for over 12 generations. Transgenic RGS9-overexpressors (RGS9-ox ( 11)) were bred into the GCAPs?/? background; half of the GCAPs?/? mice used for comparison in Figs. RG7204 nmr
1, 2, and 4 and Table 1 were transgene-negative littermates of GCAPs?/?RGS9-ox mice. All dissection and tissue preparation were performed under infrared illumination with the aid of infrared-visible converters. As previously described in Gross and Burns (10) and Krispel et?al. (11), retinas were isolated in L-15 media supplemented with bovine se rum albumin and glucose, and stored on ice. Suction electrode recordings of the outer segment membrane current were made from intact rods at 37��C in oxygenated, Ku0059436
bicarbonate-buffered Locke's solution. Brief calibrated flashes (10?ms, 500?nm) were used to elicit light-evoked responses. The average SPR amplitude was estimated by variance-to-mean analysis (3) from an ensemble of at least 25 dim flash responses (responses with amplitudes <20% of the dark current). For comparison to the model, in Fig.?5A the data from RGS9-ox and wild-type (WT) rods with normal GCAPs/Ca feedback is republished from Gross and Burns ( 10). Rogue�� SPRs of GCAPs?/? and GCAPs?/?RGS9-ox rods were easily identified by the large, steplike events that terminated abruptly after variable times. The frequency and amplitude of rogue responses were determined from responses to bright flashes that produced 10�C70 R?; rogues were identified as extended plateaus after a normal initial recovery from saturation. The duration of each rogue response was measured as the time between the beginning of the flash response and the 50%-recovery point of the steplike event. The dominant time constant of recovery (��D) for saturating responses and the time constant of recovery for dim flash responses was determined as previously described in Gross and Burns ( 10) and Krispel et?al. ( 11). <a href="http://www.selleck.cn/products/Pomalidomide
(CC-4047).html">Pomalidomide Briefly, the time in saturation was measured from the midpoint of?the flash to the time that the current recovered by 10%. The average number of R? produced by a flash was determined by first calculating the effective collecting area for each cell and multiplying this collecting area by the calibrated flash strength (as described in Gross and Burns ( 10)). For all parameters, the mean �� SE values are presented unless otherwise indicated. Statistical significance was determined by Student's t-test.