Figure 8. Reducing the temperature prolonged the α4β2 relaxation time constants and reduced the fast component fractional amplitude.
A-C, plots of the α4β2 τf, τs and If/Itotversus membrane potential at 9 and 22 °C. [ACh]= 100 nM. The symbols are the means of 5 oocytes. The error bars are ±s.e.m. The straight lines were fitted using least-squares regression. A, the α4β2 τf increased e-fold per -395 mV at 9 °C (r = 0.86, d.f. = 8, P < 0.01) and e-fold per -725 mV at 22 °C (r = 0.69, d.f. = 8, P < 0.05). The extrapolated α4β2 τf at 0 mV decreased from 11 ms at 9 °C to 3 ms at 22 °C. B, the α4β2 τs increased e-fold per -557 mV at 9 °C (r = 0.92, d.f. = 8, P < 0.01) but was not significantly correlated with voltage at 22 °C (r = 0.60>, d.f. = 7, P > 0.05). The extrapolated α4β2 τs at 0 mV was 68 ms at 9 °C. C, the slope of the α4β2 If/Itot regression line at 9 °C was 0.0025 mV−1 (r = 0.91, d.f. = 8, P < 0.01). The α4β2 If/Itot at 22 °C was not significantly correlated with voltage (r = 0.2, d.f. = 8, P > 0.10). The extrapolated α4β2 If/Itot at 0 mV was 0.6 at 9 °C.