| Autor: |
Hice, Rita, Folander, Kimberly, Salata, Joseph, Smith, Jeffrey, Sanguinetti, Michael, Swanson, Richard |
| Zdroj: |
Pflügers Archiv: European Journal of Physiology; 1994, Vol. 426 Issue 1/2, p139-145, 7p |
| Abstrakt: |
We have compared the slowly activating K currents ( I) resulting from the expression of the human, mouse, or rat I proteins in Xenopus oocytes, utilizing natural, species-dependent sequence variations to initiate structure-function studies of this channel. Differences were found between the human and rodent currents in their voltage dependence, kinetics, and sensitivity to external La. The current/voltage relationships of the human and rat I currents differed significantly, with greater depolarizations required for activation of the human channel. The first 30 s of activation during depolarizations to potentials between −10 and +40 mV was best described by a triexponential function for each of the three species variants. The activation rates were, however, significantly faster for the human current than for either of the rodent forms. Similarly, deactivation kinetics were best described as a biexponential decay for each of the species variants but the human currents deactivated more rapidly than the rodent currents. The human and the rodent forms of I were also differentially affected by external La. Low concentrations (10, 50 μM) rapidly and reversibly reduced the magnitude of the mouse and rat currents during a test depolarization and increased the deactivation rates of the tail currents. In contrast, the magnitude and deactivation rates of the human I currents were unaffected by 50 μM La. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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