Figure 3. Accumulated data: effects of ATP on spontaneous release frequency and amplitude.
The abscissa indicates [ATP] on a log scale and the ordinates indicate the frequency or amplitude of the spontaneous CICR transient. As [ATP] was decreased, the mean amplitude of the CICR transient increased to a maximum of 194.6 ± 25.5 % (mean ± s.e.m., n = 7) of the control response in the presence of 5 mm ATP. As the concentration was further reduced the mean amplitude declined slightly to 175.3 ± 18.29 % (mean ± s.e.m., n = 7). The frequency of the CICR showed an approximately linear dependence on log10[ATP], decreasing by 23.4 ± 5.24 % (mean ± s.e.m., n = 7) in the presence of 0.01 mm ATP.