Krisanda J M, Paul R J
Am J Physiol. 1983 May;244(5):C385-90. doi: 10.1152/ajpcell.1983.244.5.C385.
Previous studies (Paul, R. J. Chemical energetics of vascular smooth muscle. In: Handbook of Physiology: The Cardiovascular System. Bethesda, MD: Am. Physiol. Soc., 1980, p. 201-235) have shown that vascular oxygen consumption reaches a steady state at approximately twice the basal rate during maintenance of isometric contraction. The time course of the attainment of a metabolic steady state, the metabolic signal for the observed increase in respiration, and the contribution of endogenous phosphagens to the energetics of isometric contraction are not known with certainty. To this end, the time course of the tissue content of ATP, ADP, AMP, phosphocreatine (PCr), inorganic phosphate (Pi), and lactate were measured during a KCl-induced isometric contraction in porcine carotid artery and compared with values in the basal state. Oxygenated unpoisoned strips were frozen at 0, 0.5, 1, and 15 min of contraction, and tissue extracts were analyzed using analytical isotachophoresis. No statistically significant changes from the basal levels of ATP and PCr were measured. A small but significant increase in ADP was seen at all times. An increase in Pi of 1.25 mumol/g was observed at 0.5 min, which decreased in time. Tissue lactate content increased by 1.79 mumol/g after 1 min of contraction. The calculated range of cellular free ADP (ADPfree), 44-123 microM, may be sufficient to saturate oxidative phosphorylation. This and the apparent lack of change of ADPfree from basal during contraction suggest that it does not play a role in the coordination of metabolism and contractility. From as early as 0.5 min, when less than 40% of peak isometric force is attained, intermediary metabolism provides the total ATP required for contraction.
先前的研究（保罗，R.J. 血管平滑肌的化学能量学。载于：《生理学手册：心血管系统》。马里兰州贝塞斯达：美国生理学会，1980年，第201 - 235页）表明，在维持等长收缩期间，血管耗氧量达到稳定状态，约为基础速率的两倍。代谢稳定状态的达成时间进程、观察到的呼吸增加的代谢信号以及内源性磷酸肌酸对等长收缩能量学的贡献尚不确定。为此，在猪颈动脉的氯化钾诱导等长收缩过程中，测量了ATP、ADP、AMP、磷酸肌酸（PCr）、无机磷酸盐（Pi）和乳酸的组织含量随时间的变化，并与基础状态下的值进行比较。在收缩0、0.5、1和15分钟时，将充氧未中毒的条带冷冻，并用分析等速电泳分析组织提取物。未测得ATP和PCr的基础水平有统计学显著变化。在所有时间点均观察到ADP有小幅但显著的增加。在0.5分钟时观察到Pi增加了1.25 μmol/g，随后随时间下降。收缩1分钟后，组织乳酸含量增加了1.79 μmol/g。计算得出的细胞游离ADP（ADPfree）范围为44 - 123 μM，可能足以使氧化磷酸化饱和。这以及收缩期间ADPfree与基础状态相比明显缺乏变化表明，它在代谢与收缩性的协调中不起作用。早在0.5分钟时，当等长力峰值未达到40%时，中间代谢就提供了收缩所需的全部ATP。
