The study provides evidence for a complex oligomeric structure of KNa channels in guinea-pig ventricular myocytes, with multiple pores functionally organized into domains showing co-operative gating.
No clinical implications yet; leaves open the oligomeric organization of cardiac KNa channels for molecular studies.
Twelve short-lived subconductance levels have been recognized in potassium channels activated by intracellular Na+ (KNa channels) in membrane patches excised from guinea-pig ventricular myocytes. When stable recording was achieved over a prolonged period (> 30 min), sojourns of opening to one of two stable subconductance levels (approximately 30 and 70% of the main-state level) occurred spontaneously. These periods of activity showed similar kinetics (open and closed time distributions) to those of openings to the main-state conductance. Opening to transient sublevels was still detected during openings of the channel to the stable sublevels. These results suggest that the KNa channel has a complex oligomeric structure, in which twelve separate pores would seem to be functionally organized into either three or four domains that show a high degree of co-operativity in their gating.
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Mistry et al. (1996) studied this question.
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