Quantitative changes in the mRNA for contractile proteins and metabolic enzymes in masseter muscle of bite-opened rats.
To study the effects of bite opening on the fibre phenotypes of rat masseter, the mRNAs of four predominant myosin heavy-chain isoforms (MHC I, IIa, IId/x and IIb) and two alkali light-chain isoforms (LC1f and 3f) as well as those of two metabolic enzymes, carbonic anhydrase III (CAIII, oxidative enzyme) and glucose-phosphate isomerase (GPI, glycolytic enzyme), were measured in relation to the total RNA of masseter muscle by competitive, reverse transcriptase-polymerase chain reaction in control and bite-opened rats. Bite opening (2.8 mm increase in the vertical dimension for 1 week) significantly (P<0.05) increased the amount of MHC IIa mRNA but decreased (P<0.001) the amount of MHC IIb mRNA without changing the amount of MHC IId/x mRNA. No MHC I mRNA was found in any masseter studied. A significant (P<0.01) increase in the mRNA of LC1f associated with a decrease (P<0.05) in that of LC3f was observed after the bite opening. The CAIII mRNA increased significantly (P<0.001), while the GPI mRNA decreased (P<0.05) in association with the bite opening. These results strongly suggest that in 1 week of bite opening changes the rat masseter muscle from a glycolytic, MHC IIb-LC3f-dominant fibre to an oxidative, MHC IIa-LC1f-dominant fibre.
Ohnuki
Y
Y
Department of Physiology, Tsurumi University School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, 230-8501, Yokohama, Japan.
Saeki
Y
Y
Yamane
A
A
Yanagisawa
K
K
D000222:Adaptation, Physiological; D000818:Animals; D002256:Carbonic Anhydrases / Q000096:biosynthesis / Q000235:genetics; D018076:DNA, Complementary / Q000096:biosynthesis; D003799:Dental Stress Analysis; D004591:Electrophoresis, Polyacrylamide Gel; D005956:Glucose-6-Phosphate Isomerase / Q000096:biosynthesis / Q000235:genetics; D006019:Glycolysis; D007150:Immunohistochemistry; D008297:Male; D008406:Masseter Muscle / Q000737:chemistry / Q000378:metabolism* / Q000503:physiopathology; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D018994:Myosin Light Chains / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D017090:Occlusal Splints; D010084:Oxidation-Reduction; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014716:Vertical Dimension
D018076:DNA, Complementary; D009124:Muscle Proteins; D018994:Myosin Light Chains; D020033:Protein Isoforms; D012333:RNA, Messenger; D018995:Myosin Heavy Chains; D002256:Carbonic Anhydrases; D005956:Glucose-6-Phosphate Isomerase