Figure 1. An energy-based internal... | Rockefeller University Press

Figure 1.

$An energy-based internal solution enhances activation efficiency. (A and B) Membrane currents for a single wild-type GluN1-1a/GluN2A channel in an outside-out patch (six consecutive traces). Single channel openings are downward deflections (C, closed; O, open). Dashed vertical line indicates the start of a 1-s glutamate (1 mM) application in the continuous presence of glycine (0.1 mM). Traces in B are those in A but on an expanded time scale. Blue highlights illustrate variations to delays to first opening. Currents were sampled at 50 kHz (displayed at ∼1 kHz). Holding potential, −60 mV. The external solution was our standard external solution at pH 8, and the pipette solution (energy-based) contained added ATP and GTP (see Materials and methods). (C and D) Dwell time histogram (Sqrt, Square root) of the latency to first opening, the time between the start of agonist application to the first channel opening. For both histograms, our standard external solution was at pH 8 with the internal solution containing either no added ATP or GTP (C), as in Amin et al. (2021) or added ATP and GTP (D) (raw currents illustrated in A and B). Both histograms were best fit by two exponentials (dashed lines). The no energy internal, external at pH 8 includes results from Amin et al. (2021) (18 patches) plus four additional patches. (E) Success rate (1 − failure rate) (mean ± SEM) for averages from patches with a minimum of 20 trials (circles represent individual data points). See Table 1 for additional details. **P < 0.01, Student’s t test, P = 0.004. (F) Efficiency (η) of activation (mean ± SEM) for all patches. η is the fraction of the total number of trials that are present within the fast component of the latency histogram and represents the fraction of events that would contribute to fast synaptic transmission. **P < 0.01, Student’s t test, P = 0.0014.$

An energy-based internal solution enhances activation efficiency. (A and B) Membrane currents for a single wild-type GluN1-1a/GluN2A channel in an outside-out patch (six consecutive traces). Single channel openings are downward deflections (C, closed; O, open). Dashed vertical line indicates the start of a 1-s glutamate (1 mM) application in the continuous presence of glycine (0.1 mM). Traces in B are those in A but on an expanded time scale. Blue highlights illustrate variations to delays to first opening. Currents were sampled at 50 kHz (displayed at ∼1 kHz). Holding potential, −60 mV. The external solution was our standard external solution at pH 8, and the pipette solution (energy-based) contained added ATP and GTP (see Materials and methods). (C and D) Dwell time histogram (Sqrt, Square root) of the latency to first opening, the time between the start of agonist application to the first channel opening. For both histograms, our standard external solution was at pH 8 with the internal solution containing either no added ATP or GTP (C), as in Amin et al. (2021) or added ATP and GTP (D) (raw currents illustrated in A and B). Both histograms were best fit by two exponentials (dashed lines). The no energy internal, external at pH 8 includes results from Amin et al. (2021) (18 patches) plus four additional patches. (E) Success rate (1 − failure rate) (mean ± SEM) for averages from patches with a minimum of 20 trials (circles represent individual data points). See Table 1 for additional details. **P < 0.01, Student’s t test, P = 0.004. (F) Efficiency (η) of activation (mean ± SEM) for all patches. η is the fraction of the total number of trials that are present within the fast component of the latency histogram and represents the fraction of events that would contribute to fast synaptic transmission. **P < 0.01, Student’s t test, P = 0.0014.

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