Shal-type channels contribute to the Ca2+-independent transient outward K+ current in rat ventricle.

摘要: 1. The hypothesis that Kv4.2 and Kv4.3 are two of the essential K+ channel isoforms underlying Ca2+-independent transient outward current (It) in rat ventricle has been tested using a combination electrophysiological measurements antisense technology both native myocytes stably transfected mammalian cell line, mouse Ltk- cells (L-cells). 2. currents generated by channels L-cells exhibit rapid activation inactivation properties similar to those produced It ventricular cells. current-voltage relationships voltage dependence steady-state also very these preparations. However, recovery from is much slower (time constant, 378 ms) than (58 ms). 3. due can be blocked millimolar concentrations 4-aminopyridine L-cells; pharmacological response observed myocytes. 4. Quinidine inhibits fashion. In quinidine reduced amplitude accelerated its time course inactivation, suggesting may act as an open blocker Kv4.2, described for ventricle. 5. To provide further independent evidence contribute cells, effects 20-mer phosphorothioate oligodeoxynucleotides directed against mRNAs were examined isolated 14- 20-day-old rats, L-cells. preparations, pretreatment significantly (by approximately 55-60%). Similar reduction was oligonucleotide on 14-day-old 6. 14-day oligonucleotides did not produce larger after with either alone. 7. treated evaluate possibility cross-reactivity between mRNA. This treatment no change It, verifying lack cross-reactivity. 8. These biophysical results together data show components current,