抄録
It is reported that the N-terminal tail of Cav 1.2 (L-type) Ca2+ channel has an inhibitory function since its removal enhances channel activity. In this study, the effects of the N-terminal peptide on activity of L-type Ca2+ channels were investigated in patch-clamp inside-out patch mode in guinea pig myocytes. An application of the GST-fused N-terminal peptide (GST-NT, a.a. 6-140; 0.1, 1, 5 μM) + 3 mM ATP to the intracellular solution within 1 min after run-down induced by patch excision resulted in a dose-dependent activation of channel activity. The channel activity was 8.4%, 16.3%, and 30.9% of that recorded in the cell-attached mode, respectively, while it was 3.1% for 1 μM GST alone as control. Neither GST-NT nor ATP alone induced Ca2+ channel activity, showing a cooperative effect of GST-NT and ATP on the Ca2+ channel. At the 5th and 10th minutes after patch excision, GST N-terminal peptide (1 μM) + 3mM ATP induced Ca2+ channel activity to only 4.5% and 3.0%, respectively, revealing a time-dependent attenuation of the GST-NT effect on the Ca2+ channel. These results suggest that the N-terminal tail of Ca 1.2 Ca2+ channel plays a regulatory role in Ca2+ channel activity. [J Physiol Sci. 2008;58 Suppl:S73]
