Voltage-dependent activation in purified reconstituted sodium channels from rabbit T-tubular membranes

Journal Article · Wed Jan 01 04:00:00 EST 1986 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.83.2.488· OSTI ID:6410993

Furman, R E; Tanaka, J C; Mueller, P; Barchi, R L

The authors have examined the voltage-dependent gating of batrachotoxin-modified sodium channels purified from rabbit T-tubular membranes in two ways. First, purified channels were reconstituted into planar bilayers and single-channel properties were measured. Batrachotoxin-activated channels showed steep voltage-dependent activation with half-maximal opening probabilities at potentials between -95 and -116 mV. The single-channel conductance averaged 20 pS and was independent of membrane potential. A second approach was used to establish that this voltage dependence was a characteristic of the entire population of purified channels and not just those few channels observed in planar bilayers. Channels reconstituted into egg phosphophatidyl-choline vesicles were functionally oriented by inclusion of internal saxitoxin; vesicle membrane potentials were then generated by K/sup +/ gradients in the presence of valinomycin. All of the specific /sup 22/Na/sup +/ influx activated by batrachotoxin and blocked by saxitoxin was found to be voltage sensitive, activating between predicted membrane potentials of -100 and -50 mV. The single-channel properties of the purified T-tubular sodium channel correspond closely to those seen with native sodium channels from rat sarcolemma. The voltage-dependent activation of the bactrachotoxin-modified reconstituted channel is the same as that seen with native channels in situ or in bilayers after exposure this toxin.

• Research Organization: Univ. of Pennsylvania, Philadelphia
• OSTI ID: 6410993
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 83:2; ISSN PNASA
• Country of Publication: United States
• Language: English

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ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMALS
ANTIGENS
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BETA-PLUS DECAY RADIOISOTOPES
BIOELECTRICITY
CATIONS
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LIGHT NUCLEI
LUMINESCENCE
MAMMALS
MATERIALS
MEMBRANE TRANSPORT
MEMBRANES
MUSCLES
NUCLEI
ODD-ODD NUCLEI
RABBITS
RADIOISOTOPES
SODIUM 22
SODIUM CHLORIDES
SODIUM COMPOUNDS
SODIUM ISOTOPES
TOXIC MATERIALS
TOXINS
TRITIUM COMPOUNDS
VERTEBRATES
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