【摘要】 大鼠离体左室乳头肌固定于最适初长位,逐步递减“后荷”获得一系列等张收缩的张力、长度缩短程度和速度。结果发现:（1）收缩末期张力-长度关系（ESTLR）为指数曲线,回归方程 T=ar^-bL-K 拟合的优度明显高于线性方程拟合的优度（P<0.001）,其中 a,k 分别代表总张力和静息张力,b 为曲线的弯曲度;（2）在高钙（4mmol/L）或去甲肾上腺素(NE10^-6mol/L)作用下,ESTLR 右上移位,a,b 和无张力缩短速度 L_O 均增大（P均<0.01）,尤以高钙时的变化更明显,（3）NE 使张力-速度曲线的右上移位比高钙显著。这提示大鼠离体心肌的 ESTLR 呈非线性特征,参数 a,b 及长度轴截距 L_O 对收缩强度的变化敏感,但对收缩速度改变的敏感性可能比经典的力学指标低。更多还原

【Abstract】 A series of isotonic tension,shortening and shortening velocity were obtainedin isolated rat papillary muscles by varying the setpoint force against which themuscle shortened at optimal length.It was found that（1）end systolic tension-length relation（ESTLR）could be described by an exponential equation.T=ae^-bL—k,where a and k represent respectively the total tension and the resting ten-sion and b means curved degree and length-axis intercept（L₀）represents maximalshortening.There was a greater correlation index R² when fitted with the equa-tion compared with linear regression（P<0.001）.（2）High[Ca²⁺]₀ shifted ESTLRleftward and upward,with increased a,b and maximal shortening L₀,so did nor-epinephrine（NE）but significantly less than high[Ca²⁺]₀,whereas the changesin rates of shortening and tension rise were greater during NE infusion than duringhigh[Ca²⁺]₀ infusion.These results indicated that ESTLR was non-linear inisolated myocardium and exponential parameters a,b and L₀ were sensitive tochanges in contractile intensity,but less sensitive to changes in contractilevelocity when compared with indexes of myocardial mechanics.更多还原