Exercise-induced hyperemia unmasks regional blood flow deficit in experimental hindlimb ischemia
Exercise-induced hyperemia unmasks regional blood flow deficit in experimental hindlimb ischemia
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DOI：
10.1006/jsre.2001.6161
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发表时间：
2001-06-01
影响因子：
2.2
通讯作者：
Messina, LM
中科院分区：
文献类型：
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作者：
Brevetti, LS;Paek, R;Messina, LM
后肢缺血的许多实验模型的特征在于静息肌血流量（BF）速率的自发和快速正常化，这使得逆转肢体缺血的血管生成疗法的长期评价复杂化。我们测试了一个假设，即腓神经刺激缺血后肢会增加氧（O-2）的需求和BF率，从而揭示了严重的血流不足，这是不明显的休息。通过结扎左侧髂总动脉、股动脉及其分支在成年大鼠中诱导缺血。腓神经被刺激，以允许测量运动诱导的区域BF率与荧光微球。监测血流动力学，在缺血后3、10和24天神经刺激5 min之前和之后注射荧光微球。收获胫骨前肌（TA）和腓肠肌（GC）肌肉和皮肤并称重，并测量荧光。BF率计算为每克组织每分钟的毫升数，并与未手术对照大鼠的正常肌肉和皮肤进行比较。为了确定当每个样本递送< 400个微球时缺血肌肉中BF率测量的准确性，通过同时注射4 × 10（5）蓝色和1 × 10（5）黄绿色荧光微球来研究3只大鼠。测定不同颜色微球释放量之间的相关系数。缺血引起TA和G;C肌肉萎缩。与对照组相比，缺血性TA和GC的平均肌肉质量（作为总体重的百分比）随时间推移而降低[TA 0.13 +/- 0.05% vs 0.25 +/-0.03%，P < 0.05; GC 0.51 +/- 0.27% vs 0.70 +/-0.07%，P = 0.07（24天）]。尽管在实验组中有严重的后肢缺血的临床证据，即，压疮、肌肉萎缩和无力、静息BF率与对照组无显著差异。TA的BF率在缺血3D后为0.11ml/min/g，10 D后为0.14ml/min/g，24 D后为0.13ml/min/g。未手术对照组正常肌肉BF率平均为0.16ml/min/g（P > 0.05）。然而，在所有缺血组中，运动诱导的骨骼肌充血明显减弱。运动后，未手术对照TA的BF增加了10倍以上，达到1.95 ml/min/g，而缺血性TA在3D时BF没有增加，在10 D时增加了S倍，在24 D时增加了5倍。在GC肌肉中也观察到类似的发现。皮肤中BF率无显著差异。该微球技术在测量缺血肌肉中发现的非常低的BF率方面的准确性得到了比较两种微球注射量的显著相关系数（r = 0.99）的支持。尽管有严重后肢缺血的临床体征，但缺血组的静息BF率并未显著降低。腓神经刺激导致BF率增加10倍，并揭示了缺血组血管储备的严重不足。静息BF率并不总是准确反映严重肢体缺血模型中的血流不足，并且这种运动诱导的后肢充血模型可以更好地长期评价旨在逆转严重肢体缺血的血管生成治疗。(C)北京：科学出版社.
Many experimental models of hindlimb ischemia are characterized by spontaneous and rapid normalization of resting muscle blood flow (BF) rates which complicates the long-term evaluation of angiogenic therapies to reverse limb ischemia. We tested the hypothesis that peroneal nerve stimulation in an ischemic hindlimb would increase the oxygen (O-2) demand and BF rate, thereby unmasking a severe blood flow deficit that is not apparent at rest.Methods. Ischemia was induced in adult rats by ligation of the left common iliac, femoral arteries, and their branches. Peroneal nerves were stimulated to allow measurement of exercise-induced regional BF rates with fluorescent microspheres. Hemodynamics were monitored, Fluorescent microspheres were injected before and after 5 min of nerve stimulation 3, 10, and 24 days postischemia. The tibialis anterior (TA) and gastrocnemius (GC) muscles and skin were harvested and weighed, and fluorescence was measured. BF rate was calculated as milliters per minute per gram of tissue and compared to normal muscle and skin of unoperated control rats. In order to determine the accuracy of BF rate measurements in ischemic muscle when < 400 microspheres was delivered per specimen, 3 rats were studied by simultaneous injection of 4 x 10(5) blue and 1 x 10(5) yellow-green fluorescent microspheres. The correlation coefficient between the number of different colored microspheres delivered was measured.Results. The ischemia caused atrophy of the TA and G;C muscles. The mean muscle mass of the ischemic TA and GC as a percentage of total body weight decreased over time vs control [TA 0.13 +/- 0.05% vs 0.25 +/- 0.03%, P < 0.05; GC 0.51 +/- 0.27% vs 0.70 +/- 0.07%, P = 0.07 at 24 days (24D)]. Despite clinical evidence of severe hindlimb ischemia in experimental groups, i.e., pressure sores, muscle atrophy, and weakness, resting BF rates were not significantly different from those of control. The BF rate of the TA was of 0.11 ml/min/g after 3D of ischemia, 0.14ml/min/g after 10D, and 0.13 ml/min/g after 24D. The mean BF rate in normal muscle of unoperated controls was 0.16 ml/min/g (P > 0.05). However, the exercise-induced hyperemia in the skeletal muscle was significantly blunted in all of the ischemic groups. The unoperated control TA had a greater than 10-fold increase in BF to 1.95 ml/min/g in response to exercise while the ischemic TA had no increase in BF at 3D, S-fold increase at 10D, and a 5-fold increase at 24D. Parallel findings were noted in the GC muscles. There was no significant difference in the BF rate in the skin. The accuracy of this microsphere technique in measuring very low BF rates found in ischemic muscle was supported by the significant correlation coefficient (r = 0.99) comparing two quantities of microspheres injected simultaneously.Conclusion. Despite clinical signs of severe hindlimb ischemia, resting BF rates in the ischemic groups were not significantly decreased. Peroneal nerve stimulation resulted in up to 10-fold increase in BF rate and unmasked a severe deficit in vascular reserve in the ischemic groups. Resting BF rate is not always an accurate reflection of the flow deficit in models of critical limb ischemia, and this model of exercise-induced hindlimb hyperemia may allow better long-term evaluation of angiogenic therapies designed to reverse critical limb ischemia. (C) 2001 Academic Press.