Ricciardi L, Bottinelli R, Canepari M, Reggiani C
Institute of Human Physiology, University of Pavia, Italy.
J Mol Cell Cardiol. 1994 May;26(5):601-7. doi: 10.1006/jmcc.1994.1072.
This study was designed to assess whether maximum shortening velocity and force-velocity parameters were reduced by acidosis in rat skinned cardiac trabeculae, as reported for skinned skeletal muscle. Thin trabeculae were dissected from right ventricle of adult male Wistar rats, chemically skinned, and maximally Ca-activated at pH 7.0, 6.6 and 6.2. Maximum tension (Po), maximum shortening velocity evaluated from force-velocity curves (Vmax), and maximum power output (Wmax) were significantly reduced for exposure to pH 6.6 and 6.2. When the value at pH 7.0 is taken as reference, Po decreased by 30% and 49%, Vmax by 17% and 40% and Wmax by 30% and 60% at pH 6.6 and 6.2 respectively. A similar reduction (25% at pH 6.6 and 42% and pH 6.2) was observed when unloaded shortening velocity (Vo) was determined with the slack test method. The results obtained show that both Po and Vmax or Vo are affected by a substantial decrease in pH. The combination between significantly lower Po and Vmax gives rise to significantly lower Wmax. The reduction of maximum shortening velocity (Vmax or Vo) can be explained by assuming either the existence of an internal load or an impairment in actin-myosin interaction.
本研究旨在评估大鼠去表皮心肌小梁的最大缩短速度和力-速度参数是否如去表皮骨骼肌那样因酸中毒而降低。从成年雄性Wistar大鼠的右心室中分离出细小梁，进行化学去表皮处理，并在pH 7.0、6.6和6.2条件下进行最大钙激活。暴露于pH 6.6和6.2时，最大张力（Po）、从力-速度曲线评估的最大缩短速度（Vmax）和最大功率输出（Wmax）均显著降低。以pH 7.0时的值为参考，在pH 6.6和6.2时，Po分别降低了30%和49%，Vmax分别降低了17%和40%，Wmax分别降低了30%和60%。当用松弛测试法测定无负荷缩短速度（Vo）时，也观察到了类似的降低（pH 6.6时为25%，pH 6.2时为42%）。所得结果表明，Po和Vmax或Vo均受到pH值大幅下降的影响。Po和Vmax显著降低共同导致Wmax显著降低。最大缩短速度（Vmax或Vo）的降低可以通过假设存在内部负荷或肌动蛋白-肌球蛋白相互作用受损来解释。
