In the isolated taenia (0.4-0.6 g) of guinea-pig caecum, the intracellular phosphorous compounds and pH were investigated using 31P nuclear magnetic resonance (NMR) under various metabolic conditions. 2. The ratios of the intracellular concentration of phosphocreatine ([ PCr]) and inorganic phosphate [( Pi]) to nucleotide triphosphate ([ NTP]) were 1.71 +/- 0.14 and 0.58 +/- 0.11 (n = 25), respectively, in normal solution (32 degrees C). The intracellular pH estimated from the chemical shift of Pi was 7.05 +/- 0.06 (n = 25), agreeing well with those previously obtained. 3. In the absence of glucose, the [PCr] and [NTP] were decreased to almost a half after 150 min exposure to 40 mM-K+ solution, while [Pi] was increased 3-fold. These changes were much faster than the rate of decline in tension. When glucose was readmitted, the contractile response to K+ fully recovered in 50 min. However, this was accompanied with only a partial recovery of [PCr] and [Pi], but no recovery of [NTP]. The intracellular pH was lowered by about 0.2 of a unit, suggesting an increase in glycolysis. 4. In Ca2+-free solution, respiratory inhibition with hypoxia or CN (1 mM) only decreased [PCr], leaving [NTP] nearly unchanged. On the other hand, respiratory inhibition in excess-K+ solution containing Ca2+ (2.4 mM) severely depleted PCr and decreased [NTP] to 40%. Increasing glucose to 50 mM did not prevent these changes, although it increased tension development. 5. The simultaneous decrease of [NTP] and [PCr] during K+ contracture suggests that the activity of creatine phosphokinase is low. The recovery from respiratory inhibition was much better for [PCr] than for [NTP]. Slow, but perfect, recovery of all NTP peaks was produced by adding 1 mM-adenosine to normal solution. 6. It was suggested that tension development is closely related to the turnover rate of ATP, and not to its concentration, and that deamination of adenosine is a limiting factor in the recovery of ATP after excessive consumption.
摘要
在豚鼠盲肠分离的绦虫（0.4 - 0.6克）中，利用31P核磁共振（NMR）在各种代谢条件下研究了细胞内磷化合物和pH值。2. 在正常溶液（32℃）中，磷酸肌酸（[PCr]）和无机磷酸盐（[Pi]）与三磷酸核苷酸（[NTP]）的细胞内浓度之比分别为1.71±0.14和0.58±0.11（n = 25）。根据Pi的化学位移估算的细胞内pH值为7.05±0.06（n = 25），与先前获得的值非常吻合。3. 在无葡萄糖的情况下，暴露于40 mM - K +溶液150分钟后，[PCr]和[NTP]降至几乎一半，而[Pi]增加了3倍。这些变化比张力下降的速度快得多。当重新加入葡萄糖时，对K +的收缩反应在50分钟内完全恢复。然而，这仅伴随着[PCr]和[Pi]的部分恢复，而[NTP]没有恢复。细胞内pH值降低了约0.2个单位，表明糖酵解增加。4. 在无Ca2 +溶液中，缺氧或CN（1 mM）引起的呼吸抑制仅降低了[PCr]，[NTP]几乎不变。另一方面，在含有Ca2 +（2.4 mM）的高K +溶液中的呼吸抑制严重消耗了PCr，并使[NTP]降至40%。将葡萄糖增加到50 mM并不能防止这些变化，尽管它增加了张力的发展。5. K +挛缩期间[NTP]和[PCr]同时下降表明肌酸磷酸激酶的活性较低。[PCr]从呼吸抑制中的恢复比[NTP]好得多。向正常溶液中加入1 mM腺苷可使所有NTP峰缓慢但完全恢复。6. 有人提出，张力的发展与ATP的周转率密切相关，而与其浓度无关，并且腺苷的脱氨是过量消耗后ATP恢复的限制因素。
