Temporal response of rabbits to beta-adrenergic agonist feeding: tissue weight, calpains and calpastatin activities, and nucleic acid and protein concentrations.
Forty-eight crossbred rabbits were used in three replications of a 2 x 4 factorial arrangement to investigate the short-term responses of tissue accretion, calpains and calpastatin activity, and nucleic acid and protein concentrations to beta-adrenergic agonist (BAA) feeding. Rabbits were fed a 17% CP diet with or without 7 ppm of L644,969 and slaughtered after 1, 4, 8, or 16 d of treatment. Empty body dressing percentage and biceps femoris weight (as a percentage of empty body weight [EBW]) were significantly higher in the treated rabbits than in the controls after 16 d of treatment. Heart and liver weights (as a percentage of EBW) were higher (P < .05) after 1 d and liver weight (as a percentage of EBW) was lower (P < .05) after 16 d in treated vs controls. Except for an elevation of skeletal muscle m-calpain after 16 d, BAA-supplementation did not affect the calpain-calpastatin system. Muscle RNA concentrations and RNA:DNA ratios were higher (P < .05) in treated rabbits after 1 d and remained higher thereafter. Protein:RNA ratios were lower (P < .01) in treated than in control rabbits after 4 d and remained lower throughout the trial. Muscle DNA content was lower after 4 d and higher after 16 d; RNA content was higher after 4, 8, and 16 d; and protein content was higher after 16 d in treated vs control rabbits. Liver nucleic acid and protein concentrations were not affected by BAA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Pringle
T D
TD
Department of Animal Science, University of Nebraska, Lincoln 68583-0908.
Lonergan
S M
SM
Calkins
C R
CR
Jones
S J
SJ
Miller
P S
PS
Koohmaraie
M
M
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D001806:Blood Urea Nitrogen; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004247:DNA / Q000032:analysis; D005260:Female; D006321:Heart / Q000187:drug effects / Q000254:growth & development; D008099:Liver / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development; D024510:Muscle Development; D009124:Muscle Proteins / Q000032:analysis; D009132:Muscles / Q000737:chemistry / Q000187:drug effects; D009206:Myocardium / Q000737:chemistry; D009929:Organ Size / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology*; D012313:RNA / Q000032:analysis; D011817:Rabbits / Q000254:growth & development* / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D002135:Calcium-Binding Proteins; D009124:Muscle Proteins; D011725:Pyridines; C061557:6-amino-alpha-(((1-methyl-3-phenylpropyl)amino)methyl)-3-pyridine methanol; D012313:RNA; C033668:calpastatin; D004247:DNA; D002154:Calpain