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Weakly electric fish of the families Gymnotidae and Hypopomidae (Gymnotiformes) are able to locate the electric discharges from conspecifics or from dipole electrodes, and they demonstrate this by making rapid, well-directed approaches toward these electrical sources. A video tracking system was used to follow the movements of electric fish in a large tank(More)
1. Patch clamp recording techniques have been used to investigate the block by amiloride of the mechanosensitive cation-selective channel in frog (Xenopus laevis) oocytes. 2. Cell-attached and outside-out patch recording configurations were employed to study the differences in block produced when amiloride was present at either the extracellular (external)(More)
In this article, the actions, mechanisms and applications of various ions and drugs that interact with MG channels have been discussed. At present, no compound has been found that displays the high specificity and affinity exhibited by tetrodotoxin or alpha-bungarotoxin that proved so useful in the functional and structural characterization of the(More)
Practical limitations of the patch-clamp technique when recording mechanogated membrane ion channels are considered. Mechanical overstimulation of the patch or the cell from excessive suction/pressure protocols induces morphological and functional changes. In particular, the plasma membrane becomes decoupled from the underlying cytoskeleton to form either(More)
Mechanosensitive (MS) channels are expressed in a wide range of cell types and have been implicated in diverse functions, including osmoregulation and mechanoreception. The majority of previous studies on single MS channels have been carried out on nonsensory cells and have dealt with the steady-state properties of the channel. Here we measure the dynamic(More)
Gymnotiform electric fish are capable of locating and approaching an electrically discharging conspecific over a range of 1-2 m in a behavior called passive electrolocation. This paper investigates the movements of two species in experiments with approaches to stationary dipoles that are either silenced or jumped to a new direction during an approach.(More)
1. The ion selectivity of a membrane ion conductance that is inactivated by extracellular calcium (Ca2+o) in Xenopus oocytes has been studied using the voltage-clamp technique. 2. The reversal potential of the Ca2+o-sensitive current (Ic) was measured using voltage ramps (-80 to +40 mV) as a function of the external concentration (12-240 mM) of NaCl or KCl.(More)
The effects of Mg2+ on single mechanosensitive (MS) channel currents recorded from Xenopus oocytes were studied using cell-attached and inside-out patch configurations. Mg2+ both permeates and blocks MS channels. Under symmetrical ionic conditions, the blocking effects of Mg2+ can be described by a Hill coefficient of 0.9 at +/-100 mV and IC50s of 0.12 mM(More)