Control APs | Variable APs | |
---|---|---|
Threshold, mV | −39.7 ± 0.8 | −52.2 ± 1.0* |
Overshoot, mV | 33.6 ± 0.9 | 30.1 ± 1.7† |
Half width, ms | 1.22 ± 0.05 | 0.77 ± 0.05* |
Rate of rise, V · s−1 | 193 ± 8 | 218 ± 12 |
Rate of fall, V · s−1 | 44 ± 2 | 66 ± 5* |
Ratio of rate of rise to rate of fall | 4.6 ± 0.2 | 3.5 ± 0.3‡ |
fAHP peak, mV | −67.4 ± 0.9 | −69.7 ± 1.1 |
sAHP peak, mV | −71.0 ± 1.1 |
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Values are means ± SE. Measurements were made on individual spontaneous APs generated at low frequency (0.2–1.0 Hz). The APs were selected from each cell on the basis of the threshold, being either close to the average (control APs; n = 35), or >8.0 mV negative to the average (variable APs; n = 18). AP, action potential; fAHP and sAHP, fast and slow afterhyperpolarization, respectively. *P < 0.001. †P < 0.05. ‡P < 0.01.