Abstract
In the present study, patch-clamp techniques have been used to investigate the effect of trimethyltin chloride (Met3SnCl) on the slow vacuolar (SV) channels in vacuoles from red beet (Beta vulgaris L.) taproots. Activity of SV channels has been measured in whole-vacuole and cytosolic side-out patch configurations. It was found that addition of trimethyltin chloride to the bath solution suppressed, in a concentration-dependent manner, SV currents in red beet vacuoles. The time constant, τ, increased significantly in the presence of the organotin. When single channel activity was analyzed, only little channel activity could be recorded at 100 μM Met3SnCl. Trimethyltin chloride added to the bath medium significantly decreased (by ca. threefold at 100 μM Met3SnCl and at 100 mV voltage, as compared to the control medium) the open probability of single channels. Single channel recordings obtained in the presence and absence of trimethyltin chloride showed that the organotin only slightly (by <10%) decreased the unitary conductance of single channels. It was also found that Met3SnCl significantly diminished the number of SV channel openings, whereas it did not change the opening times of the channels. Taking into account the above and the fact that under the here applied experimental conditions (pH = 7.5) Met3SnCl is a non-dissociated (more lipophilic) compound, we suggest that the suppression of SV currents observed in the presence of the organotin results probably from its hydrophobic properties allowing this compound to translocate near the selectivity filter of the channel.
Highlights
In the last several decades, organotin compounds have become an important pollutant due to their widespread use in industry and agriculture as fungicides, biocides, antifouling agents, wood preservatives and plastics stabilizers [1,2,3,4]
Taking into account the above and the fact that under the here applied experimental conditions Met3SnCl is a non-dissociated compound, we suggest that the suppression of slow vacuolar (SV) currents observed in the presence of the organotin results probably from its hydrophobic properties allowing this compound to translocate near the selectivity filter of the channel
The main objective of the present study was to determine the effect of trimethyltin chloride on SV channels activity in vacuoles isolated from red beet (Beta vulgaris L.) taproots
Summary
In the last several decades, organotin compounds have become an important pollutant due to their widespread use in industry and agriculture as fungicides, biocides, antifouling agents, wood preservatives and plastics stabilizers [1,2,3,4]. Their high toxicity was established e.g. in algae and aquatic plants [5, 6]. Despite the large number of papers on organotins, the precise mechanism of their toxic effect on plant cells still remains poorly understood
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