Voltage-sensitive K-currents in sympathetic neurons and their modulation by neurotransmitters

A description is given of methods for voltage clamping and for studies of the several varieties of K-currents occurring in sympathetic neurons. Conclusions were derived chiefly from experiments conducted on bullfrog lumbar paravertebral sympathetic ganglia but observations made were compared with results obtained from studies of neurons of the rat superior cervical ganglion. Discussion is given of means used for revealing and identifying these currents and for studying actions of drugs, calcium, etc. and circumstances such as membrane state on the four quite distinct time- and voltage-dependent K-currents: IK, IC, IA and IM. The latter (IM) is under direct presynaptic control and the major focus of the paper is on this current and its role. However, considerable information is given concerning the characteristic of the other three (IK, IC and IA).