Effects of thyroxine on transmembrane resting potentials of skeletal muscle cells in culture

✍ Scribed by Dr. S. R. Sampson; Rena R. Bannett; A. Shainberg

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 403 KB
• Volume: 8
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490080404

✦ Synopsis

The effect of thyroxine (T3) was studied on the transmembrane resting potential (Em) of rat skeletal muscle cells in culture. In agreement with previous studies, we found the Em of developing muscle cells to increase with age from Day 3 to Day 7 or 8, at which time a plateau is reached. The values of Em we obtained (-65 to -75 mV) were 15-20 mV higher than those (-50 to -55 mV) reported by others. Treatment of mature myotubes with T4 resulted in a significant increase in resting Em. There was only a slight difference between T4-treated and control cells with regard to the relation bctwcen cxtracellular K + concentration and resting Em. Within 20-30 min of exposure to ouabain (lop4 -10p3M) resting Em of both T,-treated and control cells had fallen to about the same value. This effect was reversible. Thus, T, stimulateb the activity uf an electrogenic NaX-ATPase in the membrane of cultured skcletal muscle cells.