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Na+ channel mis‐expression accelerates K+ channel development in embryonic Xenopus laevis skeletal muscle.
Author(s) -
Linsdell P,
Moody W J
Publication year - 1994
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1994.sp020370
Subject(s) - xenopus , skeletal muscle , myocyte , tetrodotoxin , biology , endogeny , channel blocker , microbiology and biotechnology , medicine , endocrinology , chemistry , gene , biochemistry , calcium
1. The normal developmental pattern of voltage‐gated ion channel expression in embryonic skeletal muscle cells of the frog Xenopus laevis was disrupted by introduction of cloned rat brain Na+ channels. 2. Following injection of channel mRNA into fertilized eggs, large Na+ currents were observed in muscle cells at the earliest developmental stage at which they could be uniquely identified. Muscle cells normally have no voltage‐gated currents at this stage. 3. Muscle cells expressing exogenous Na+ channels showed increased expression of at least two classes of endogenous K+ currents. 4. This increase in K+ current expression was inhibited by the Na+ channel blocker tetrodotoxin, suggesting that increased electrical activity caused by Na+ channel mis‐expression triggers a compensatory increase in K+ channel expression. 5. Block of endogenous Na+ channels in later control myocytes retards K+ current development, indicating that a similar compensatory mechanism to that triggered by Na+ channel mis‐expression operates to balance Na+ and K+ current densities during normal muscle development.