Pulmonary hypertension is a noninfectious disease of cattle at altitudes > 1524 m (5,000 ft). Mean pulmonary arterial pressures (PAP) are used as an indicator for pulmonary hypertension in cattle. High PAP cattle (≥50 mmHg) entering the feedlot at moderate elevations have lower feed efficiency as compared to low PAP cattle (< 50 mmHg). The impact of pulmonary arterial pressure on mitochondrial function, oxidative phosphorylation (OXPHOS) protein abundance, and meat color was examined using longissimus lumborum (LL) from high (98 ± 13 mmHg; n = 5) and low (41 ± 3 mmHg; n = 6) PAP fattened Angus steers (live weight of 588 ± 38 kg) during early postmortem period (2 and 48 h) and retail display (days 1 to 9), respectively. High PAP muscle had greater (P = 0.013) OXPHOS-linked respiration and proton leak-associated respiration than low PAP muscles at 2 h postmortem but rapidly declined to be similar (P = 0.145) to low PAP muscle by 48 h postmortem. OXPHOS protein expression was higher (P = 0.045) in low PAP than high PAP muscle. During retail display, redness, chroma, hue, ratio of reflectance at 630 and 580 nm, and metmyoglobin reducing activity decreased faster (P < 0.05) in high PAP steaks than low PAP. Lipid oxidation significantly increased (P < 0.05) in high PAP steaks but not (P > 0.05) in low PAP. The results indicated that high PAP caused a lower OXPHOS efficiency and greater fuel oxidation rates under conditions of low ATP demand in premortem beef LL muscle; this could explain the lower feed efficiency in high PAP feedlot cattle compared to low PAP counterparts. Mitochondrial integral function (membrane integrity or/and protein function) declined faster in high PAP than low PAP muscle at early postmortem. LL steaks from high PAP animals had lower color stability than those from the low PAP animals during simulated retail display, which could be partially attributed to the loss of muscle mitochondrial function at early postmortem by ROS damage in high PAP muscle.

中文翻译：

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适度海拔的养肥安格斯牛的肺动脉压影响零售展示期间的早期死后线粒体功能和肉色

肺动脉高压是牛的一种非传染性疾病 1524 米（5,000 英尺）。平均肺动脉压 (PAP) 用作牛肺动脉高压的指标。与低 PAP 牛（<50 毫米汞柱）相比，以中等海拔进入饲养场的高 PAP 牛（≥50 毫米汞柱）具有较低的饲料效率。使用腰最长肌 (LL) 从高 (98 ± 13 mmHg; n = 5) 和低 (41 ± 3 mmHg; n) 检查肺动脉压对线粒体功能、氧化磷酸化 (OXPHOS) 蛋白丰度和肉色的影响= 6) 在验尸早期（2 小时和 48 小时）和零售展示（第 1 至 9 天）期间分别使用 PAP 育肥安格斯牛（活重 588 ± 38 千克）。高 PAP 肌肉有更大的 (P = 0. 013) OXPHOS 相关呼吸和质子泄漏相关呼吸在死后 2 小时比低 PAP 肌肉强，但在死后 48 小时迅速下降到与低 PAP 肌肉相似 (P = 0.145)。与高 PAP 肌肉相比，低 PAP 肌肉中的 OXPHOS 蛋白表达更高 (P = 0.045)。在零售陈列期间，高 PAP 牛排比低 PAP 牛排的发红度、色度、色调、630 和 580 nm 反射比以及高铁肌红蛋白还原活性下降得更快 (P < 0.05)。脂质氧化在高 PAP 牛排中显着增加 (P < 0.05)，但在低 PAP 中没有增加 (P > 0.05)。结果表明，在生前牛肉 LL 肌肉的 ATP 需求低的情况下，高 PAP 会导致较低的 OXPHOS 效率和较高的燃料氧化率；这可以解释与低 PAP 对应物相比，高 PAP 饲养场牛的饲料效率较低。在死后早期，高 PAP 肌肉的线粒体整体功能（膜完整性或/和蛋白质功能）比低 PAP 肌肉下降得更快。在模拟零售展示期间，来自高 PAP 动物的 LL 牛排的颜色稳定性低于来自低 PAP 动物的颜色稳定性，这可能部分归因于高 PAP 肌肉中 ROS 损伤在早期死后肌肉线粒体功能的丧失。