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首页> 外文期刊>American Journal of Physiology >Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium.
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Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium.

机译：在冬眠的心肌中对结前和结后交感神经刺激的钝性功能反应。

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Regional reductions in norepinephrine-tracer uptake are found in pigs with hibernating myocardium. Clinical studies would suggest that this is evidence for denervation; however, the functional responses to sympathetic stimulation have not been evaluated, and our previous studies with beta-adrenergic stimulation have not suggested denervation hypersensitivity. Therefore, pigs were chronically instrumented to produce hibernating myocardium characterized by chronic regional dysfunction and histological viability. Open-chest studies were performed to determine changes in regional function in response to both pre- and postjunctional stimulation. Regional segment shortening was reduced at rest in hibernating myocardium compared with controls (13 +/- 3% vs. 27 +/- 3%, P 0.004). During stellate ganglion stimulation, regional function increased in both groups of animals (P = 0.008 vs. baseline), but the increase in hibernating myocardium was blunted compared with controls (Delta%, 3 +/- 2% vs. 8 +/- 3%, P = 0.04). Similar results occurred with intracoronary tyramine (10 mug/kg). Functional improvement during intravenous epinephrine infusion (0.35 mug.kg(-1).min(-1)) was also blunted in hibernating myocardium compared with controls (Delta%, 7 +/- 1% vs. 15 +/- 2%, P = 0.04). Even when the improvement in function was expressed relative to the reduced baseline, there was no evidence for catecholamine-mediated hypersensitivity in hibernating myocardium. We therefore conclude that functional responses to both pre- and postjunctional sympathetic stimulation are blunted in pigs with hibernating myocardium. In contrast to previous studies of infarcted, denervated, and acutely stunned myocardium, there is no catecholamine-induced hypersensitivity in hibernating myocardium. These data suggest a downregulation in functional responses to stimulation that would protect hibernating myocardium from demand-induced ischemia at the expense of contractile reserve during sympathetic stimulation.
机译：在冬眠心肌的猪中发现了去甲肾上腺素示踪剂摄取的区域减少。临床研究表明，这是神经支配的证据。然而，尚未评估对交感神经刺激的功能性反应，而我们先前对β-肾上腺素能刺激的研究也未提示神经支配性超敏反应。因此，猪被长期用于产生冬眠心肌，其特征在于慢性区域功能障碍和组织学活力。进行了开胸研究，以确定对结前和结后刺激的反应区域功能的变化。与对照组相比，冬眠的心肌在休息时的区域节段缩短减少了（13 +/- 3％对27 +/- 3％，P 0.004）。在星状神经节刺激期间，两组动物的区域功能均增强（相对于基线，P = 0.008），但是与对照相比，冬眠心肌的增加变钝了（Delta％，3 +/- 2％vs. 8 +/- 3） ％，P = 0.04）。冠状动脉内酪胺（10杯/千克）也发生了类似的结果。与对照组相比，冬眠心肌时静脉内肾上腺素输注（0.35 mug.kg（-1）.min（-1））的功能改善也减弱了（Delta％，7 +/- 1％与15 +/- 2％， P = 0.04）。即使相对于降低的基线表现出功能的改善，也没有证据表明儿茶酚胺介导的超敏反应冬眠心肌。因此，我们得出结论，在有冬眠心肌的猪中，对结前和结后交感神经刺激的功能反应均减弱。与先前关于梗死，神经失调和急性惊呆的心肌的研究相反，冬眠心肌没有儿茶酚胺引起的超敏反应。这些数据表明，对刺激的功能反应的下调将保护冬眠的心肌免受需求诱发的局部缺血，而以交感刺激期间的收缩储备为代价。

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