Effect of Trimethyltin Chloride on Slow Vacuolar (SV) Channels in Vacuoles from Red Beet (Beta vulgaris L.) Taproots

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.

Effect of Auxin (IAA) on the Fast Vacuolar (FV) Channels in Red Beet (Beta vulgaris L.) Taproot Vacuoles

“…The experimental data were stored and elaborated using Patch-Master, Fit-Master software (HEKA Electronic, Lambrecht, Germany) and Dell Statistica (data analysis software system), version 13 (Dell, Texas, TX, USA). The details of the experiments and an analysis of the results were performed in accordance with our earlier papers [ 25 , 38 ]. The open probability was calculated (using FitMaster software) as the total opening time normalized to the total recording time and the number of active channels in a patch (see also [ 26 , 39 ]).…”

Role of auxin (IAA) in the regulation of slow vacuolar (SV) channels and the volume of red beet taproot vacuoles

“…The electrophysiological experiments were performed in whole-vacuole and excised cytosolic side-out patch configuration. The recordings were made using an EPC-7 Plus amplifier (List-Medical-Electronic, Darmstadt, Germany), as was recently described by Trela et al [ 40 ]. For signal filtration a five-pole Bessel filter was used with sampling frequency of 1 to 100 kHz.…”

“…For signal filtration a five-pole Bessel filter was used with sampling frequency of 1 to 100 kHz. The patch pipettes were prepared from borosilicate glass tubes (Kimax-51, Kimble Products, Toledo, Ohio, USA) in accordance with the procedure previously described by us [ 40 ]. Voltage pulse within a range of 300 to 900 mV combined with gentle suction let gain the access to the vacuole interior.…”

“…Data were stored and elaborated using PatchMaster, FitMaster (HEKA Electronic, Lambrecht, Germany) and Dell Statistica (data analysis software system), version 13. Analysis of the results was performed in accordance with our earlier paper [ 40 ]. The opening probability was calculated as the total opening time normalized to the total recording time and the number of active channels in a patch [ 42 ].…”