Abstract
Fast-twitch skeletal muscles contain more neuronal-type nitric oxide synthase (nNOS) than slow-twitch muscles because nNOS is present only in fast (type II) muscle fibers. Chronic in vivo electrical stimulation of tibialis anterior and extensor digitorum longus muscles of rabbits was used as a method of inducing fast-to-slow fiber type transformation. We have studied whether an increase in muscle contractile activity induced by electrical stimulation alters nNOS expression, and if so, whether the nNOS expression decreases to the levels present in slow muscles. Changes in the expression of myosin heavy chain isoforms and maximum velocity of shortening of skinned fibers indicated characteristic fast-to-slow fiber type transformation after 3 wk of stimulation. At the same time, activity of NOS doubled in the stimulated muscles, and this correlated with an increase in the expression of nNOS shown by immunoblot analysis. These data suggest that nNOS expression in skeletal muscle is regulated by muscle activity and that this regulation does not necessarily follow the fast-twitch and slow-twitch pattern during the dynamic phase of phenotype transformation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
