Blue light activates potassium-efflux channels in flexor cells from Samanea saman motor organs via two mechanisms
SCIE
SCOPUS
- Title
- Blue light activates potassium-efflux channels in flexor cells from Samanea saman motor organs via two mechanisms
- Authors
- Suh, S; Moran, N; Lee, Y
- Date Issued
- 2000-07
- Publisher
- AMER SOC PLANT PHYSIOLOGISTS
- Abstract
- Light induced leaflet movement of Samanea saman depends on the regulation of membrane transporters in motor cells. Blue light (BL) stimulates leaflet opening by inducing K+ release from the flexor motor cells. To elucidate the mechanism of K+-efflux (K-D)-channel regulation by light, flexor motor cell protoplasts were patch-clamped in a cell-attached configuration during varying illumination. Depolarization elicited outward currents through single open K-D channels. Changes in cell membrane potential (E-M) were estimated by applying voltage ramps and tracking the change of the apparent reversal potential of K-D-channel current. BL shifted E-M in a positive direction (i.e. depolarized the cell) by about 10 mV. Subsequent red light pulse followed by darkness shifted E-M oppositely (i.e. hyperpolarized the cell). The BL-induced shifts of E-M were not observed in cells pretreated with a hydrogen-pump inhibitor, suggesting a contribution by hydrogen-pump to the shift. BL also increased K-D-channel activity in a voltage-independent manner as reflected in the increase of the mean net steady-state patch conductance at a depolarization of 40 mV relative to the apparent reversal potential (G(@40)). G(@40) increased by approximately 12 pS without a change of the single-channel conductance, possibly by increasing the probability of channel opening. Subsequent red-light and darkness reversed the change in G(@40). Thus, K+ efflux, a determining factor for the cell-volume decrease of flexor cells, is regulated by BL in a dual manner via membrane potential and by an independent signaling pathway.
- Keywords
- PLASMA-MEMBRANE; GUARD-CELLS; K+ CHANNELS; PATCH-CLAMP; SIGNAL-TRANSDUCTION; ION CHANNELS; VICIA-FABA; H+-ATPASE; RED-LIGHT; PROTOPLASTS
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/19928
- DOI
- 10.1104/pp.123.3.833
- ISSN
- 0032-0889
- Article Type
- Article
- Citation
- PLANT PHYSIOLOGY, vol. 123, no. 3, page. 833 - 843, 2000-07
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