Download Supplemental Figure 3

Supplemental Figure 3. A) The T-type Ca2+-channel antagonist NNC 55-0396 at a
concentration of 10 M completely inhibits both T-type and non-T-type Ca2+-channels in
human -cells. In this experiment, Ba2+ (2.6 mM) was used as the charge carrier (cf.
Huang, L. et al. (2004) J Pharmacol Exp Ther 309:193-199). B) The unspecific
inhibitory effect of 1 M NNC 55-0396 on non-T-type Ca2+-currents is reversible after
washout of the drug. The traces were recorded before, 1 and 5 minutes after addition of
the blocker and after its removal as indicated. In hormone secretion measurements, NNC
55-0396 was therefore washed out after a 15 min pre-incubation before the start of the
experiment. In patch-clamp experiments using the same protocol, the peak Ca2+-current
averaged 10.2±1 pA/pF (n=18) and 13.2±1.1 pA/pF (n=16, p<0.02) with and without pretreatment with NNC 55-09936. The sustained current was not significantly different
between both groups (NNC 4.6±0.4 pA/pF vs control 5.0±0.6 pA/pF). The inhibition of
T-type-channels usually developed faster than the inhibition of high-voltage activated
currents after addition of the drug.