TY - JOUR
T1 - Single channel properties of newly synthesized acetylcholine receptors following denervation of mammalian skeletal muscle
AU - Henderson, Leslie P.
AU - Lechleiter, James D.
AU - Brehm, Paul
PY - 1987/6/1
Y1 - 1987/6/1
N2 - We have examined the single channel properties of newly synthesized acetylcholine (ACh) receptors in denervated adult mouse muscle. Patch-clamp recordings were made on freshly isolated fibers from flexor digitorum brevis (fdb) muscles that had been denervated in vivo for periods up to 3 wk. Muscles were treated with a-bungarotoxin (α-BTX), immediately before denervation, in order to block pre-existing receptors. Denervated fibers exhibited two types of ACh receptor channels, which differed in terms of single channel conductance (45 and 70 pS) and mean channel open time (~7 and 2.5 ms, respectively). In contrast to innervated muscle, where only 3% of the total openings were contributed by the low-conductance channel type, >80% of the openings in the nonsynaptic membrane of denervated muscle were of this type. Importantly, a similar increase in the proportion of low-conductance channels was observed for recordings from synaptic membrane after denervation. These data argue against theproposal that, in denervated muscle, the low-conductance channels undergo continued conversion to the high-conductance type focally at the site of former synaptic contact. Rather, our findings provide additional support for the idea that the functional properties of ACh receptors are governed uniformly by the state of innervation of the fiber and not by proximity to the site of synaptic contact.
AB - We have examined the single channel properties of newly synthesized acetylcholine (ACh) receptors in denervated adult mouse muscle. Patch-clamp recordings were made on freshly isolated fibers from flexor digitorum brevis (fdb) muscles that had been denervated in vivo for periods up to 3 wk. Muscles were treated with a-bungarotoxin (α-BTX), immediately before denervation, in order to block pre-existing receptors. Denervated fibers exhibited two types of ACh receptor channels, which differed in terms of single channel conductance (45 and 70 pS) and mean channel open time (~7 and 2.5 ms, respectively). In contrast to innervated muscle, where only 3% of the total openings were contributed by the low-conductance channel type, >80% of the openings in the nonsynaptic membrane of denervated muscle were of this type. Importantly, a similar increase in the proportion of low-conductance channels was observed for recordings from synaptic membrane after denervation. These data argue against theproposal that, in denervated muscle, the low-conductance channels undergo continued conversion to the high-conductance type focally at the site of former synaptic contact. Rather, our findings provide additional support for the idea that the functional properties of ACh receptors are governed uniformly by the state of innervation of the fiber and not by proximity to the site of synaptic contact.
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U2 - 10.1085/jgp.89.6.999
DO - 10.1085/jgp.89.6.999
M3 - Article
C2 - 2440981
AN - SCOPUS:0023217125
SN - 0022-1295
VL - 89
SP - 999
EP - 1014
JO - Journal of General Physiology
JF - Journal of General Physiology
IS - 6
ER -