| Autor: |
Bouteau, François, Bousquet, Ulrike, Pennarun, Anne-Marie, Convert, Monique, Dellis, Olivier, Cornel, Daniel, Rona, Jean-Pierre |
| Předmět: |
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| Zdroj: |
Physiologia Plantarum; Sep96, Vol. 98 Issue 1, p97-104, 8p |
| Abstrakt: |
The purpose of our work was to investigate the functioning of K+ channels in protoplasts of laticifers of Hevea brasiliensis Muell. Arg., anastomosed into a network devoid of large central vacuoles, after tapping stress. Physiological functions such as proton pump activity and uptake of sucrose (a rubber precursor) were maintained, when the voltage-clamp method was used in vivo to record the whole-cell K+ current during the stress response. A time-dependent inward current was induced in 50 mM KCl and rapidly inactivated (about 100 ms). The activation potential of this inward K+ channel was not closely dependent on EK. This would be coherent with the ‘valve model’ of Schroeder and Fang (1991, Proc. Natl. Acad. Sci. USA 88: 11583–11587) involving the activation of a H+-pump accounting for the K+ uptake observed in laticiferous cells under stress. The activation half-time of outward currents was clearly voltage dependent: from about 350 to 60 ms for 125 and 155 mV, respectively. Time-dependent outward current sensitivity to 5 mM BaCl2 or CaCl2 or to 5 µM Erythrosin B showed that the K+ channels could be Ca2+-dependent. Because of the positive values of the activation potential of the outward current, the possibility opens that an action potential exists, these cells being specialized for stress response. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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