Effects of chronic sympathectomy on muscle fibre composition ISO-myosin patterns, protein synthesis and calcium content in canine gracilis muscle.
We have previously reported functional and histological studies in five beagle dogs with unilateral lumbar sympathectomy. Three months later, fatiguability in the gracilis muscles was increased on the denervated sides, and this was associated with an increase in the relative distribution of FT fibres. Biochemical studies now show that these changes were associated with an increase in cytosolic protein without change in DNA content; this is consistent with an increase in cell size. There was a reduction in the proportion of slow myosin light chain isoforms from 50 +/- 7 to 34 +/- 6%. Noradrenaline levels were increased on the denervated sides but this may reflect greater vascularity. Calcium content did not correlate with fibre type but there was a positive relation with both noradrenaline content (r = 0.73; P less than 0.05) and DNA content (r = 0.84; P less than 0.05). It is concluded that sympathectomy induces several biochemical changes in skeletal muscle which constitute a change and increase in fast myosin light chain synthesis and a corresponding fibre type transformation.
Karlsson
J
J
Department of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden.
Cummins
P
P
Smith
H J
HJ
Berggren
P O
PO
Saartok
T
T
D000818:Animals; D002118:Calcium / Q000032:analysis*; D003600:Cytosol / Q000032:analysis; D004247:DNA / Q000032:analysis; D004285:Dogs; D009132:Muscles / Q000032:analysis*; D009218:Myosins / Q000032:analysis*; D009638:Norepinephrine / Q000032:analysis; D014176:Protein Biosynthesis; D013562:Sympathectomy
D004247:DNA; D009218:Myosins; D002118:Calcium; D009638:Norepinephrine