Effect of growth promoters on pig muscle structural protein and proteolytic enzyme levels in vivo and in vitro.
To elucidate the biochemical mechanism by which the growth hormone porcine somatotrophin (PST) promotes skeletal muscle growth, we have determined the activity of a comprehensive range of protein catabolizing proteolytic enzymes and structural proteins (determined by analytical electrophoresis, SDS-PAGE) in longissimus dorsi muscle from control and PST treated pigs. There was no significant difference in the levels of muscle structural proteins, or in the activity of muscle proteolytic enzymes at point of slaughter in control or PST treated animals. Similarly, in post-mortem muscle proteolysis time course experiments at pH 5.5 or pH 7.5, there was no significant difference in the rate of structural protein degradation by endogenous muscle proteases (determined via SDS-PAGE) using muscle from control or PST treated animals. In addition, investigation of a range of beta-agonist related drugs (clenbuterol, salbutamol, pirbuterol, fenoterol) showed no effect (10(-4)-10(-8) M) in vitro on the activity of individual protease types in control muscle, or on the degradation rate of muscle structural proteins by endogenous proteases in time course experiments at pH 5.5 or pH 7.5.(ABSTRACT TRUNCATED AT 250 WORDS)
Blanchard
P
P
Division of Neurobiology, School of Neurosciences, University of Newcastle upon Tyne, UK.
Ellis
M
M
Maltin
C
C
Falkous
G
G
Harris
J B
JB
Mantle
D
D
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002369:Castration; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D024510:Muscle Development; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects*; D013552:Swine
D000318:Adrenergic beta-Agonists; D009124:Muscle Proteins; D013006:Growth Hormone; D010450:Endopeptidases