Figure 4. Dependence of open times on [cGMP]. All data were filtered at 2 kHz. (A) Fast open time τo1 and slow open time τo2 of single cGMP-gated channels as function of [cGMP]. Kinetic constants were measured at 7, 20, 70, and 700 μM cGMP and at −50 and +50 mV. Parentheses indicate values at 7 and 70 μM, respectively. 16–63 traces of 500-ms duration were analyzed. When switching from −50 to +50 mV, both τo1 and τo2 increased at 70 μM cGMP and even more so at 700 μM cGMP, whereas at 7 and 20 μM cGMP, no statistically significant increase of either τo1 and τo2 was observed. (B) Voltage-dependent incidence of the relative contribution of fast and slow exponential in the open-time histograms as function of [cGMP]. Plotted is the ratio An (+50 mV)/An (−50 mV). At low [cGMP], A2 (+50 mV)/A2 (−50 mV) is larger than A1 (+50 mV)/A1 (−50 mV), suggesting that the contribution of the slow exponential is more influenced by voltage than that of the fast exponential.
Image published in: Benndorf K et al. (1999)
© 1999 The Rockefeller University Press. Creative Commons Attribution-NonCommercial-ShareAlike license
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