A Potassium-Selective Channel in Isolated Lymnaea Stagnalis Heart Muscle Cells

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Abstract
Lymnaea stagnalis heart ventricle muscle cells, isolated by enzymatic dispersion, are suitable for patch clamp recording. A channel has been identified which is primarily selective for potassium, although it also appears to conduct sodium. This channel is not blocked by 4-aminopyridine or tetraethylammonium but is sensitive to quinidine. The relationship between the membrane potential, the external potassium concentration and the channel currents, when compared with results obtained from whole cell recording, suggests that this channel could mediate a large part of the cell's resting conductance. The probability of this channel being open is increased by stretching the patched cell membrane. This has led to speculations about further possible functional roles for this channel.