FMRFamide and membrane stretch as activators of the Aplysia S-channel

Vandorpe, David H.; Small, Daniel L.; Dabrowski, André; Morris, Catherine E.

doi:10.1016/s0006-3495(94)80749-0

Cited by 48 publications

(27 citation statements)

References 28 publications

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“…Because membrane tension (stretch) can modulate a diversity of voltage and ligand gated ion channels in addition to stretchactivated channels (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)34) as well as some ion transporters (18,19), our findings suggest that some actions of depolarization on inside-out and on-cell patches of membrane formed with borosilicate pipettes may reflect voltage-induced changes in membrane tension rather than the direct effects of voltage. 4.…”

Section: Discussionmentioning

confidence: 88%

“…Thus, the voltage-induced membrane displacement is associated with sufficient tension to activate MS channels. Because various ion channels and pumps have been shown to be modulated by membrane tension (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), it is possible that voltage modulation of some channels or transporters studied in patch pipettes may reflect changes in membrane tension rather than, or in addition to, the direct effects of voltage.…”

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confidence: 99%

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Voltage-induced membrane displacement in patch pipettes activates mechanosensitive channels

Gil

Silberberg

Magleby

1999

Proc. Natl. Acad. Sci. U.S.A.

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The patch-clamp technique allows currents to be recorded through single ion channels in patches of cell membrane in the tips of glass pipettes. When recording, voltage is typically applied across the membrane patch to drive ions through open channels and to probe the voltage-sensitivity of channel activity. In this study, we used video microscopy and single-channel recording to show that prolonged depolarization of a membrane patch in borosilicate pipettes results in delayed slow displacement of the membrane into the pipette and that this displacement is associated with the activation of mechanosensitive (MS) channels in the same patch. The membrane displacement, Ϸ1 m with each prolonged depolarization, occurs after variable delays ranging from tens of milliseconds to many seconds and is correlated in time with activation of MS channels. Increasing the voltage step shortens both the delay to membrane displacement and the delay to activation. Preventing depolarization-induced membrane displacement by applying positive pressure to the shank of the pipette or by coating the tips of the borosilicate pipettes with soft glass prevents the depolarization-induced activation of MS channels. The correlation between depolarization-induced membrane displacement and activation of MS channels indicates that the membrane displacement is associated with sufficient membrane tension to activate MS channels. Because membrane tension can modulate the activity of various ligand and voltage-activated ion channels as well as some transporters, an apparent voltage dependence of a channel or transporter in a membrane patch in a borosilicate pipette may result from voltage-induced tension rather than from direct modulation by voltage. M echanosensitive (MS) ion channels can act as transducers for the senses of touch, hearing, balance, and proprioception and also seem to be involved in the regulation of cell volume (1-3). MS channels in patches of membrane in the tips of patch pipettes are readily activated when the membrane is stretched by the application of negative pressure to the shank of the patch pipette (4). The stretching of the membrane patch by negative pressure is thought to activate the channels by increased tension in the membrane (5). When the pressure is released, the channels then readily deactivate. In addition to stretch activation, some MS channels can also be activated by voltage (1). In this regard, depolarization of membrane patches from Xenopus oocytes activates endogenous MS channels in the patch after prolonged delays of typically 1-20 s (6). After stepping the voltage back to negative potentials, the MS channels then deactivate over several seconds. The delayed activation is observed for both on-cell and excised patches and typically occurs in a cooperative manner, with all channels activating over a short period of time compared with the duration of the delay to activation.We have shown recently that the delayed activation of the MS channels is not observed in outside-out patches, in membrane outside of the patc...

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Section: Discussionmentioning

confidence: 88%

mentioning

confidence: 99%

Voltage-induced membrane displacement in patch pipettes activates mechanosensitive channels

Gil

Silberberg

Magleby

1999

Proc. Natl. Acad. Sci. U.S.A.

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“…The SACs may associate with other membrane proteins to modulate their activity (Vandorpe et al 1994); those can be water channels (aquaporins) that are involved in the water transportation across membranes and may increase up to 1000-fold the diffusion rate of water molecules through membranes. In fish spermatozoa, the putative presence of aquaporins comes from observations where sperm motility is sensitive to low concentrations of inhibitors of aquaporins such as HgCl 2 , Abascal et al 2007.…”

Section: Analysis Of Marine Fish Spermatozoamentioning

confidence: 99%

Marine fish spermatozoa: racing ephemeral swimmers

Cosson

Groison²,

Suquet³

et al. 2008

Reproduction

144

150

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After a long period of spermatogenesis (several weeks to months), marine fish spermatozoa are delivered at male spawning in seawater (SW) at the same time as ova. In some fish species, as the ova micropyle closes quickly after release, these minute unicells, the spermatozoa, have to accomplish their task of reaching the micropyle within a very brief period (several seconds to minutes), for delivery of the haploid male genetic information to the ova. To achieve this goal, their high-performance motile equipment, the flagellum, must fully activate immediately on contact with the SW and then propel the sperm cell at an unusually high initial velocity. The cost of such 'hyperactivity' is a very rapid consumption of intracellular ATP that outstrips the supply. The spermatozoa become rapidly exhausted because mitochondria cannot compensate for this very fast flagellar energy consumption. Therefore, any spermatozoon ends up with two possibilities: either becoming exhausted and immotile or reaching the egg micropyle within its very short period of forward motility (in the range of tens of seconds) before micropyle closure in relation to both contact of SWand cortical reaction. The aim of the present review is to present step by step the successive events occurring in marine fish spermatozoa from activation until their full arrest of motility. The present knowledge of activation mechanisms is summarized, as well as a description of the motility parameters characterizing the motility period. As a complement, in vitro results on axonemal motility obtained after demembranation of flagella bring further understanding. The description of the sperm energetic content (ATP and other high energy compounds) and its evolution during the swimming period is also discussed. A general model aiming to explain all the successive cellular events occurring immediately after the activation is presented. This model is proposed as a guideline for understanding the events governing the sperm lifespan in the marine fish species that reproduce through external fertilization.

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“…Of these, however, only a single rate constant is significantly sensitive to tension . Conversely, channels that have been previously characterized as ligand gated (Vandorpe et al, 1994) or voltage sensitive (Gu et al, 2001) may turn out to be mechanically sensitive Morris, 2004;Calabrese et al, 2002). This poses an intriguing problem in evolution: how to design structures with the necessary flexibility to support large conformational changes (Jiang et al, 2003b;Jiang et al, 2003a) while avoiding unnecessary mechanical activation?…”

Section: Introductionmentioning

confidence: 99%