In this letter, a comparison between three types （two linear and one nonlinear） of models of skeletal muscle stiffness is shown. Results are compared with experimental data for biceps brachii in the case of muscle s...In this letter, a comparison between three types （two linear and one nonlinear） of models of skeletal muscle stiffness is shown. Results are compared with experimental data for biceps brachii in the case of muscle stretching and with the Hill equation for a biological muscle. It is shown that results for nonlinear stiffness model in case of length-force relationship fits to the experimental data.展开更多
文摘为了研究乳酸菌对苏尼特羊肌纤维特性和肉品质的影响及其作用机理,选择12只、3月龄健康无病的纯种苏尼特羊,随机分为2组:对照组(基础日粮)和乳酸菌组(基础日粮、2 g/只(植物乳杆菌添加量为3×1010 cfu/g)),进行为期90 d的饲喂试验。屠宰后取其背最长肌,利用ATPase组织化学染色法和实时荧光定量技术对肌纤维特性、肌球蛋白重链(Myosin Heavy Chains,MyHCs)和线粒体生物发生相关基因的mRNA表达量进行测定,此外测定代谢酶活力、生长性能和肉品质,探究肌纤维特性存在差异的原因。结果表明:乳酸菌显著提高了肌肉排酸24 h的pH值(P<0.01),降低肉的黄度值(P<0.05)和蒸煮损失(P<0.01)。肌纤维分析结果显示乳酸菌显著提高了ⅡA型肌纤维的数量比例(P<0.01),降低了ⅡB型肌纤维的数量比例(P<0.01),同时MyHCⅠ(P<0.05)、MyHCⅡa(P<0.01)、MyHCⅡx(P<0.01)mRNA表达量均显著提高。乳酸菌显著提高了琥珀酸脱氢酶(Succinate Dehydrogenase,SDH)的酶活力(P<0.05),降低了乳酸脱氢酶(Lactic Dehydrogenase,LDH)的酶活力(P<0.05)。此外,乳酸菌显著提高了腺苷酸活化蛋白激酶α1(AMP-activated protein kinaseα1,AMPKα1)(P<0.01)、沉默信息调节因子1(Sirtuin1,SIRT1)(P<0.01)和细胞色素C氧化酶Ⅳ(Cytochrome c oxidase,COXⅣ)(P<0.05)mRNA表达量。综上所述,日粮添加乳酸菌可能通过提高AMPKα1、SIRT1和COXⅣmRNA表达量促进骨骼肌线粒体生物发生,增强肌肉的氧化代谢能力,促进苏尼特羊的肌纤维类型发生转化,进而改善肉品质,研究结果为改善绵羊的肉用品质提供参考。
基金supported by"Master Programme"of the Foundation for Polish Science
文摘In this letter, a comparison between three types （two linear and one nonlinear） of models of skeletal muscle stiffness is shown. Results are compared with experimental data for biceps brachii in the case of muscle stretching and with the Hill equation for a biological muscle. It is shown that results for nonlinear stiffness model in case of length-force relationship fits to the experimental data.
