FIGURE 10.

Time dependence of Kv1.2 current amplitude modulation by PKA activation and inhibition and effect of Rp-CPT-cAMPS on basal and 8-Br-cAMP-induced increase in Kv1.2 current. A, representative whole-cell currents during 250-ms voltage steps to +20 mV (applied at 15-s intervals) recorded before (0 min) and when a stable change in current amplitude was detected at 4 min for Kv1.2-WT (WT; n = 3) and at 14 min for Kv1.2-S449A (S449A; n = 4) as well as the mean (±S.E.) fractional change in Kv1.2-WT (n = 3) and S449A (n = 4) end pulse current (n = 4) due to treatment with 8-Br-cAMP (1 mm). B, representative whole-cell currents (evoked by voltage protocol in A) recorded before (0 min) and when a stable change in current amplitude was detected at 5.75 min for Kv1.2-WT (WT) and at 6 min for Kv1.2-S449A (S449A) as well as the mean (±S.E.) fractional change in Kv1.2-WT (n = 4) and S449A (n = 3) end pulse current due to bath treatment with Rp-CPT-cAMPS (25 μm). C, representative Kv1.2-WT and Kv1.2-S449A whole-cell currents (evoked by protocol in A) recorded immediately after membrane rupture (0 min) and after 6 and 6.75 min, respectively, of dialysis with Rp-CPT-cAMPS (25 μm) as well as the mean (±S.E.) fractional change in Kv1.2-WT (n = 4) and S449A (n = 3) end pulse current due to Rp-CPT-cAMPS. D, representative Kv1.2-WT and Kv1.2-S449A whole-cell currents (evoked by protocol in A) before (0) and after 5.75 and 6.75 min of treatment with 8-Br-cAMP (1 mm), respectively, after dialysis with Rp-CPT-cAMPS (25 μm) as well as the mean (±S.E.) fractional change in end pulse current (n = 3 in each group) due to 8-Br-cAMP in the presence of Rp-CPT-cAMPS. The asterisks in A–D indicate values for S449A mutant were significantly different from Kv1.2-WT by unpaired Student's t test (p < 0.05).