Аннотация
The repolarization phase of cardiac action potential is prone to aberrant
excitation that is common in cardiac patients. Here, we demonstrate
that this phase is markedly sensitive to Ca$^2+$ because of the
surprising existence of a Ca$^2+$-activated K$^+$ currents
in cardiac cells. The current was revealed using recording conditions
that preserved endogenous Ca$^2+$ buffers. The Ca$^2+$-activated
K$^+$ current is expressed differentially in atria compared with
ventricles. Because of the significant contribution of the current
toward membrane repolarization in cardiac myocytes, alterations of
the current magnitude precipitate abnormal action potential profiles.
We confirmed the presence of a small conductance Ca$^2+$-activated
K$^+$ channel subtype (SK2) in human and mouse cardiac myocytes
using Western blot analysis and reverse transcription-polymerase
chain reaction and have cloned SK2 channels from human atria, mouse
atria, and ventricles. Because of the marked differential expression
of SK2 channels in the heart, specific ligands for Ca$^2+$-activated
K$^+$ currents may offer a unique therapeutic opportunity to
modify atrial cells without interfering with ventricular myocytes.
- 13679367
- acid
- acid,
- amino
- animals,
- apamin,
- base
- blotting,
- calcium-activated,
- channels,
- cloning,
- data,
- dna
- gov't,
- heart,
- homology,
- humans,
- male,
- mice,
- molecular
- molecular,
- non-p.h.s.,
- p.h.s.,
- potassium
- primers,
- research
- sequence
- sequence,
- support,
- u.s.
- western,
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