Fig. 5.
Adenosine depolarizes spinal motoneurons. A: voltage-clamp recording from a spinal motoneuron during bath application of 75 μM adenosine (Vh = −60 mV). Adenosine induced an inward current in motoneurons held at −60 mV. B: example trace of 2.5-mV steps between −75 and −52.5 mV in control, adenosine, and wash conditions. Adenosine caused an increase in input resistance. C: averaged data (n = 11) showing the I-V relationship of the adenosine-induced current revealed by subtracting control I-V relationships from those in the presence of adenosine. D: current-clamp recording showing repetitive action potential firing in a ventral horn interneuron in response to the injection of a square current pulse in control, adenosine, and wash. E: averaged data (n = 8) for control, adenosine, and wash showing that adenosine had no effect on frequency-current relationships.