Characterization of thyroid hormone effects on Na-K pump and membrane potential of cultured rat skeletal myotubes

Journal Article · Mon Aug 01 04:00:00 EDT 1988 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-123-2-891· OSTI ID:6772168

Brodie, C; Sampson, S R

The purpose of this study was to characterize the effects of thyroid hormone on the Na-K pump and resting membrane potential (EM) of rat skeletal myotubes in culture. Myotubes were obtained from fetal (19-21 day) or neonatal rats (1-2 day) by serial trypsinization and maintained in culture for up to 10 days. Cells were treated with T4 or T3 on day 6 or 7, and measurements were made of EM, (/sup 3/H)ouabain binding, and ouabain-sensitive /sup 86/Rb uptake at various times thereafter. Hormone treatment increased the values of all three variables within 24 h, plateau levels being attained by 48-72 h. Cycloheximide and actinomycin D totally blocked the effects of thyroid hormone when added together to the cells, thus suggesting that protein synthesis is necessary for the effects of these hormones. Scatchard analysis showed that the new receptors have lower ouabain affinity than those in control. Blockade of spontaneously occurring action potentials with tetrodotoxin, which blocks voltage-dependent Na channels, or Na/H antiporter with amiloride, abolished the hormone effects seen after 24 h and significantly reduced those obtained after 48 h of hormone treatment. The results demonstrate that thyroid hormone-induced increased amount and activity of the electrogenic Na-K pump in cultured myotubes occurs, at least in part, in response to an initial effect to increase Na influx. Moreover, the findings are consistent with the concept that the Na-K pump plays an important role in regulation of EM in this preparation.

• Research Organization: Bar-Ilan Univ., Ramat-Gan (Israel)
• OSTI ID: 6772168
• Journal Information: Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 123:2; ISSN ENDOA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALI METALS
AMINO ACIDS
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
CARBOHYDRATES
CARBOXYLIC ACIDS
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CELL CONSTITUENTS
CELL CULTURES
CELL MEMBRANES
CYCLOHEXIMIDE
DAYS LIVING RADIOISOTOPES
DRUGS
ELEMENTS
FUNCTIONS
FUNGICIDES
GLYCOSIDES
HORMONES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
METALS
MINUTES LIVING RADIOISOTOPES
MUSCLES
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
OUABAIN
PEPTIDE HORMONES
PESTICIDES
POTASSIUM
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
RUBIDIUM 86
RUBIDIUM ISOTOPES
SODIUM
STROPHANTHINS
THYROID HORMONES
THYROXINE
TRACER TECHNIQUES
TRIIODOTHYRONINE
TRITIUM COMPOUNDS
VERTEBRATES