ISSN:
1432-2013
Keywords:
Key words Insect gap junctions
;
Lipophilic agents
;
Chemical uncoupling
;
Slow current transitions
;
Vm-sensitive gating
;
n-Alkanols
;
Arachidonic acid
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Experiments were carried out on preformed cell pairs and induced cell pairs of an insect cell line (mosquito Aedes albopictus, clone C6/36). The coupling conductance, g j, was determined with the dual voltage-clamp method. Exposure of preformed cell pairs to lipophilic agents, such as long-chain n-alkanols (n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol) or arachidonic acid, provoked a decrease in g j. Hyperpolarization of both cells led to a recovery of g j. Systematic studies revealed that this phenomenon is caused by a shift of the sigmoidal relationship g j(ss) = f(V m) towards more negative values of V m (where g j(ss) = conductance at steady-state; V m = membrane potential). The shift was dose dependent, it developed with time and was reversible. The longer the hydrocarbon chain of n-alkanols, the lower was the concentration required to produce a given shift. Besides shifting the function g j(ss) = f(V m), arachidonic acid decreased the maximal conductance, g j(max). Single-channel records gained from induced cell pairs revealed that the lipophilic agents interfere with the V m-sensitive slow channel gating mechanism. Application provoked slow current transitions (transition time: 5–40 ms) between an open state of the channel (i.e. main state or residual state) and the closed state; subsequently, fast channel transitions (transition time: 〈 2 ms) involving the main state and the residual state ceased completely. Hyperpolarization of V m or washout of the lipophilic agents gave rise to the inverse sequence of events. The single-channel conductances γ j(main state) and γ j(residual state) were not affected by n-heptanol. We conclude that long-chain n-alkanols and arachidonic acid interact with the V m-sensitive gating mechanism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004240050517
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