Biochemistry of anterior, medial, and posterior genioglossus muscle in the rat.
The tongue plays a vital role in swallowing actions. However, tongue muscles have been understudied, and it is unclear if tongue muscles are homogeneous with respect to muscle fiber-type distribution. We examined myosin heavy chain (MHC) composition of anterior, medial, and posterior sections of the genioglossus muscle (GG) using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in ten adult (9 months old) male Fischer 344/Brown Norway hybrid rats. We found that Type IIx MHC predominated in the anterior, medial, and posterior regions of the GG muscle (p=0.002), followed by IIa, then IIb. The anterior GG contained a significantly greater (p=0.004) proportion of Type IIa than did the medial or posterior regions, while the posterior GG contained a significantly greater (p=0.002) proportion of Type IIb MHC than did the medial or anterior GG. Accordingly, we found variable expression of MHC isoforms across anterior, medial, and posterior portions of the GG muscle, with more fast-contracting isoforms found posteriorly. Because motor control of the tongue requires precise and rapid movements for bolus manipulation and airway protection, variable expression of MHC isoforms along the anteroposterior axis of the GG muscle may be required to efficiently achieve deglutition and maintenance of airway patency.
Volz
Lana M
LM
Division of Otolaryngology-Head & Neck Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-7375, USA.
Mann
Laura B
LB
Russell
John A
JA
Jackson
Michelle A
MA
Leverson
Glen E
GE
Connor
Nadine P
NP
D000328:Adult; D000818:Animals; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000737:chemistry*; D009218:Myosins / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D014059:Tongue / Q000294:innervation*
D009218:Myosins