Figure 8.

The temperature-sensitive current is primarily mediated by Cav1.2 subunits. A, Agarose gel depicting a single product for Cav1.2 and Cav1.3 after real-time PCR amplification of CA1 tissue from 11-d-old rats. B, Amount of Cav1.2 and Cav1.3 mRNA normalized to GAPDH. C, Recordings of the current response of a CA1 pyramidal cell in a slice from a Cav 1.3 KO mouse in response to a slow voltage ramp (using 2 mm Ba²⁺ as charge carrier) obtained at low (28.2°C, black trace) and high (38.6°C, gray trace) temperature. All five of the cells that were tested in these mice showed the temperature-sensitive current. D, The voltage at which the current peaked plotted versus temperature for cells obtained from control animals (open symbols; n = 11) and Cav 1.3 KO animals (filled symbols; n = 5). The voltage shift in Cav1.3 KO mice (−0.87 mV/°C) was similar to that in control animals (−0.90 mV/°C), suggesting that Cav1.3 subunits are not critical for the temperature sensitivity of the current. E, Voltage trace showing the temperature response of a CA1 hippocampal pyramidal cell from a Cav1.3 KO mouse measured using whole-cell current clamp; bottom trace, simultaneous bath temperature recording. F, Summary of the fraction of cells that depolarized in response to temperature increase in wild-type rats (control) and in Cav1.3 KO mice. Internal solution was K-gluconate (see Materials and Methods) in both cases. Data from 41 and 8 cells, respectively.