di Prampero P E, Meyer M, Cerretelli P, Piiper J
Pflugers Arch. 1978 Oct 18;377(1):1-8. doi: 10.1007/BF00584367.
Thermally isolated gastrocnemii were stimulated to exhaustion, by rhythmic isotonic (70 N) tetanic contractions, during complete occlusion of blood flow. Enthalpy change (h = work + heat) and work output (w) (kJ/kg) were obtained from records of deep muscle temperature and shortening. The lactate produced (LA, mol/kg) was measured in the outflow after reestablishement of blood flow. The following relationships were obtained: h = 76LA + 1.2, and w = 19.8LA + 0.30. As the energy liberated at exhaustion by alactic energy sources (approximately P and O2 stores) is constant, deltah/deltaLA = 76 (+/- 10.5; S.E.) kJ/mol is the enthalpy change for lactate formation (delta HLA). The neutralization heat was estimated on muscle homogenates at 12kJ/mol, leaving approximately 64 kJ/MOL for deltaH of LA formation proper. The mechanical efficiencies of work related to LA formation (ELA) and of that not related to LA formation (EnonLA) were practically identical (0.25). From these values and from deltaHLA, the enthalpy change of approximately P splitting was estimated in the range of 52--62kJ/mol, depending on the value of the ratio delta approximately P/deltaLA assumed in the calculation.
对热隔离的腓肠肌进行刺激直至疲劳，刺激方式为在完全阻断血流期间进行有节奏的等张（70牛）强直收缩。通过深层肌肉温度和缩短记录获取焓变（h = 功 + 热）和功输出（w）（千焦/千克）。在恢复血流后，测量流出物中产生的乳酸（LA，摩尔/千克）。得到以下关系：h = 76LA + 1.2，以及w = 19.8LA + 0.30。由于无氧能量来源（大约是磷酸肌酸和氧气储备）在疲劳时释放的能量是恒定的，所以Δh/ΔLA = 76（±10.5；标准误）千焦/摩尔是乳酸形成的焓变（ΔHLA）。在肌肉匀浆上估计中和热为12千焦/摩尔，那么LA形成本身的ΔH约为64千焦/摩尔。与LA形成相关的功的机械效率（ELA）和与LA形成无关的功的机械效率（EnonLA）实际上是相同的（0.25）。根据这些值和ΔHLA，根据计算中假设的Δ磷酸肌酸/ΔLA比值，估计磷酸肌酸分解的焓变范围在52 - 62千焦/摩尔之间。
