Figure 1. [3H]-NA release in response to electrical field stimulation or nicotine: effects of TTX and Cd2+.
A, effect of TTX on S2/S1 ratios of transmitter release induced by electrical field stimulation. Indicated concentrations of TTX were added to the superfusion buffer 8 min before and during the second stimulus, S2. Means and s.e.m., n = 6-15 individual cultures. B, effect of Cd2+ on S2/S1 ratios of transmitter release induced by electrical field stimulation. Indicated concentrations of Cd2+ were added to the superfusion buffer 8 min before and during S2. Means and s.e.m., n = 6. C, basal transmitter release, and the release induced by 100 μM nicotine (15 s, indicated by arrows). •, control buffer containing 2 mM Ca2+; ○, superfusion buffer without (arrow at 20 min) or with (arrow at 40 min) 2 mM Ca2+. Means and s.e.m., n = 3. D, effects of 1 μM TTX or 100 μM Cd2+ on S2/S1 ratios of transmitter release induced by 100 μM nicotine. TTX or Cd2+ was added to the superfusion buffer 8 min before and during S2. Means and s.e.m., n = 12 (control, Ctr) or 6 (TTX and Cd2+). S2/S1 ratios in the presence of TTX or Cd2+ do not differ significantly (P > 0.05, Mann-Whitney test). E, effect of TTX on S2/S1 ratios of transmitter release induced by 100 μM nicotine. Indicated concentrations of TTX were added to the superfusion buffer 8 min before and during S2. Means and s.e.m., n = 6. F, effect of Cd2+ on S2/S1 ratios of transmitter release induced by 100 μM nicotine in the presence of TTX. TTX (1 μM) was included in the superfusion buffer throughout the collection of the fractions. Indicated concentrations of Cd2+ were added to the superfusion buffer 8 min before and during S2. S2/S1 ratios in the presence of Cd2+ differ from S2/S1 ratios of controls only at 300 μM Cd2+ (P < 0.01, Mann-Whitney test). Data are means and s.e.m., n = 6.