ISSN:
1432-1424
Schlagwort(e):
giant axon
;
potassium channel
;
potassium gating
;
potassium inactivation
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Chemie und Pharmazie
Notizen:
Summary Measurements were made of the kinetic and steady-state characteristics of the potassium conductance in the giant axon of the crabsCarcinus maenas andCancer pagirus. The conductance increase during depolarizing voltage-clamp pulses was analyzed assuming that two separate types of potassium channels exist in these axons (M. E. Quinta-Ferreira, E. Rojas and N. Arispe,J. Membrane Biol. 66:171–181, 1982). It is shown here that, with small concentrations of conventional K+-channel blockers, it is possible to differentially inhibit these channels. The potassium channels with activation and fast inactivation gating (m3h, Hodgkin-Huxley kinetics) were blocked by external application of 4 amino-pyridine (4-AP). The potassium channels with standard gating (n4, Hodgkin-Huxley kinetics) were preferentially inhibited by externally applied tetraethylammonium (TEA). The differential blockage of the two types of potassium conductance changes suggests that they represent two different populations of potassium channels. It is further shown here that blocking the early transient conductance increase leads to the inhibition of the repetitive electrical activity induced by constant depolarizing current injection in fibers fromCardisoma guanhumi.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01872210
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