Properties of single potassium channels in cultured primary astrocytes

Abstract

The patch-clamp technique was used to characterize the single channel ion currents in primary cultures of rat astrocytes. The most dominant channel type, which was found in over half of the inside-out membrane patches, was a potassium channel. The measured reversal potential was −67 mV, which is close to the calculated Nernst potential ions (−80 mV). These potassium channels activated with burst of very brief openings. Once activated the channels did not inactivate. The measured probabilities of the channels to be closed showed at least 3 different modes of channel behaviour; one voltage-independent and two voltage-dependent modes. During each activity-mode a ‘main’ conductance level plus two other conductance levels were recorded. In some recordings a pronounced outward rectification could also be seen.