Sensky P L, Parr T, Bardsley R G, Buttery P J
Department of Applied Biochemistry and Food Science, University of Nottingham, United Kingdom.
J Anim Sci. 1996 Feb;74(2):380-7. doi: 10.2527/1996.742380x.
The relationship between plasma epinephrine and postmortem activity of the calpain system in porcine longissimus muscle was investigated. Two groups of Large White pigs were continuously infused intravenously with either placebo (control) or epinephrine (treated) at a rate of .15 micrograms.kg-1.min-1 for a period of 1 wk before slaughter. Samples of longissimus muscle were taken at 0, 1, 2, 4, 8, 24, 48, and 192 h (t0 to t192) after slaughter and immediately snap-frozen in liquid nitrogen for subsequent analysis of mu-calpain, m-calpain, and calpastatin activity. Epinephrine infusion had no effect on the activities of mu- and m-calpain at t0. Calpastatin activity at t0 was increased (P < .01) in treated pigs by 97%. The ratio of total calpain:calpastatin activity at t0 was reduced (P < .01) in treated pigs. The activity of mu-calpain decreased rapidly after slaughter, irrespective of treatment, dropping to less than 10% of the initial activity within 8 h. The activity of m-calpain also decreased over the first 8 h, although the rate of decrease was less (P < .05) in treated pigs. Consequently, m-calpain activity remained greater in treated pigs compared with controls throughout the period normally associated with tenderization. Postmortem values for calpastatin activity tended to be highly variable, with activities being similar between control and treated pigs within 1 h after slaughter. Over the entire 192 h sampling period, calpastatin activity decreased (P < .001), although the effect was independent of treatment. In general the results imply that variations in plasma epinephrine concentrations, which may naturally occur as part of the stress response, perturb the calpain enzyme system.
研究了猪背最长肌中血浆肾上腺素与钙蛋白酶系统宰后活性之间的关系。两组大白猪在屠宰前1周内，以0.15微克·千克⁻¹·分钟⁻¹的速率静脉持续输注安慰剂（对照组）或肾上腺素（处理组）。屠宰后0、1、2、4、8、24、48和192小时（t0至t192）采集背最长肌样本，并立即在液氮中速冻，随后分析μ-钙蛋白酶、m-钙蛋白酶和钙蛋白酶抑制蛋白的活性。肾上腺素输注对t0时μ-和m-钙蛋白酶的活性没有影响。处理组猪在t0时钙蛋白酶抑制蛋白活性增加（P < 0.01），增幅为97%。处理组猪在t0时总钙蛋白酶与钙蛋白酶抑制蛋白活性的比值降低（P < 0.01）。无论处理如何，屠宰后μ-钙蛋白酶的活性迅速下降，在8小时内降至初始活性的10%以下。m-钙蛋白酶的活性在最初8小时内也有所下降，尽管处理组猪的下降速率较小（P < 0.05）。因此，在通常与嫩化相关的整个时期内，处理组猪的m-钙蛋白酶活性始终高于对照组。钙蛋白酶抑制蛋白活性的宰后值往往变化很大，屠宰后1小时内对照组和处理组猪的活性相似。在整个192小时的采样期内，钙蛋白酶抑制蛋白活性下降（P < 0.001），尽管这种影响与处理无关。总体而言，结果表明，作为应激反应一部分可能自然发生的血浆肾上腺素浓度变化会扰乱钙蛋白酶酶系统。
