title: The role of ultimate pH in proteolysis and calpain/calpastatin activity in bovine muscle.
abstract: Of a total of three Friesian cows, two of which had been treated with adrenalin before slaughter, Mm longissimus (LO), supraspinatus (SS), triceps brachii (TB) and rectus abdominis (RA) were sampled at different times post mortem (pm). pH, calpain/calpastatin activities and degradation of myofibrillar proteins, as evidenced by SDS-PAGE, were assessed. Contraction characteristics were measured by determining myofibrillar ATPase activities. Adrenalin treatment resulted in a high ultimate pH (6.48 +/- 0.40) and a faster decline pm of calpain I activity. The effect was similar in all four investigated muscles (72.4 +/- 5.4% decline at 24 h pm). The decline in calpain I activity in the control muscles was muscle-dependent and ranged from 22.8-74.3% at 24 h pm. Differences in ultimate pH did not lead to distinct rates of breakdown of proteins with molecular weights lower than that of myosin heavy chain. Calpastatin levels were muscle-dependent and correlated with myofibrillar ATPase activity (r = -0.99). In a second experiment Mm rectus abdominis (RA) and psoas major (PM) of adrenalin-treated (n = 6) and control (n = 6) Friesian-Holstein calves were sampled at 1 and 29 h pm for assessment of calpain activities. At seven days pm the M longissimus (LO) was sampled for tenderness evaluation. pH values were measured at 30 min, 4 h and 29 h pm. Adrenalin treatment resulted in a higher ultimate pH in the three muscles. Higher ultimate pH resulted in lower calpain activities in the RA at 29 h pm (P less than or equal to 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Science of Food of Animal Origin, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
authors.forename: G H
authors.initials: GH
authors.lastname: Geesink
authors.forename: A
authors.initials: A
authors.lastname: Ouali
authors.forename: F J
authors.initials: FJ
authors.lastname: Smulders
authors.forename: A
authors.initials: A
authors.lastname: Talmant
authors.forename: C
authors.initials: C
authors.lastname: Tassy
authors.forename: F
authors.initials: F
authors.lastname: Guignot
authors.forename: H L
authors.initials: HL
authors.lastname: van Laack
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism*; D002417:Cattle; D004837:Epinephrine / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000201:enzymology*; D009210:Myofibrils / Q000378:metabolism; D011180:Postmortem Changes
chemical_list: D002135:Calcium-Binding Proteins; D009124:Muscle Proteins; C033668:calpastatin; D002154:Calpain; D000251:Adenosine Triphosphatases; D004837:Epinephrine