Voltage-activated potassium currents in isolated motor neurons from the jellyfish Polyorchis penicillatus.
1. We describe two voltage-activated potassium currents in the swim motor neurons (SMNs) of the hydrozoan jellyfish, Polyorchis penicillatus. Recordings from neurons isolated in primary cultures were made using the tight-seal, whole-cell technique. 2. One current, IK-fast, turned on rapidly (time to peak = 6-15 ms), was half-activated at -10 to 0 mV, decayed with two exponential phases (tau were approximately 70 ms and approximately 1 s), and was half-inactivated by prepulses around -53 mV. It likely plays an important role in regulating the duration of SMN action potentials. IK-fast has features shared by delayed rectifiers and A-like currents in other invertebrates and vertebrates. 3. Another current, IK-slow, elicited from a holding potential of -30 mV, exhibited a slow onset (tau = 65-250 ms), was half-activated approximately +24 mV, exhibited a shallower voltage dependence than IK-fast, and did not inactivate. It was slower than most known delayed rectifiers.
Przysiezniak
J
J
Department of Zoology, University of Alberta, Edmonton, Canada.
Spencer
A N
AN
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D046508:Culture Techniques; D009046:Motor Neurons / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D037401:Scyphozoa / Q000502:physiology*; D013550:Swimming / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*
D015221:Potassium Channels