Repetitive stimulation of rat skeletal muscle increased LC2 phosphate content from 0.21 to 0.51 mol phosphate/mol LC2, which positively correlated with potentiation of peak twitch tension.
Does repetitive stimulation or isoproterenol alter LC2 phosphorylation in rat skeletal muscle?
LC2 phosphorylation increases with repetitive stimulation in rat skeletal muscle and correlates with peak twitch tension potentiation, suggesting a physiological role.
Absolute Event Rate: 0.51% vs 0.21%
Phosphorylation of the myosin light chain 2 (LC2) subunit was examined in rat fast-twitch and slow-twitch skeletal muscles in response to repetitive stimulation at 23 and 35 degrees C and on incubation of fast-twitch skeletal muscle with isoproterenol. After a 1-s tetany at 35 degrees C, LC2 phosphate content in extensor digitorum longus muscle increased rapidly and transiently from 0.21 to 0.51 mol phosphate/mol LC2. This pattern of phosphorylation was similar to that observed at 23 degrees C. Increases in LC2 phosphate content were dependent on the frequency and duration of stimulation. In soleus muscle LC2 phosphate content was minimal following a 1-s tetany but increased markedly following more prolonged tetanies. On incubation of extensor digitorum longus muscle with isoproterenol (20 microM), LC2 phosphate content did not change, whereas phosphorylase a levels increased. A positive correlation existed between LC2 phosphate content and potentiation of peak twitch tension in both types of muscles, suggesting a physiological function for LC2 phosphorylation.
Manning et al. (Mon,) reported a other. Repetitive stimulation and isoproterenol incubation was evaluated on LC2 phosphate content. Repetitive stimulation of rat skeletal muscle increased LC2 phosphate content from 0.21 to 0.51 mol phosphate/mol LC2, which positively correlated with potentiation of peak twitch tension.