Figure 7.

The effects of temperature on inwardly rectifying K⁺ currents. Steady-state inward currents evoked by 100-ms voltage pulses from −150 to −15 mV in 5-mV increments from a holding potential of −70 mV at 20°C before (A) and after (B) application of extracellular 1 mM Ba²⁺ from a single type II taste-bud cell in physiological pipette and bath solutions (described in materials and methods). Representative of >5 independent experiments. C: representative families of inwardly rectifying K⁺ currents evoked by 100-ms voltage pulses from −160 to −5 mV in 5-mV increments from a holding potential of −70 mV at various temperatures as indicated in physiological pipette and bath solutions. D: steady-state inward current-voltage (I-V) relations at different temperatures: 10°C (∇, n = 7); 15°C (Δ, n = 7); 20°C (•, n = 27); 25°C (♦, n = 7); and 30°C (Ο, n = 23). Inward currents were determined at the end of 100-ms pulses and normalized to the whole cell capacitance. E: steady-state inward rectifying currents (pA/pF) at −150 mV: 10°C (−28.8 ± 10.8, n = 7, P < 0.0005); 15°C (−32.3 ± 24.9, n = 7, P < 0.005); 20°C (−70.5 ± 25.6, n = 27); 25°C (−85.3 ± 11.2, n = 7, P = 0.149); and 30°C (−95.6 ± 39.7, n = 23, P < 0.05). The current-temperature relation for inward currents at −150 mV indicates an average Q₁₀ of 2.5. P values were obtained from Student’s t test, compared with data at 20°C.