<原著>覚醒犬を用いた心表面冠動脈の反応性拡張に関する研究

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概要

• 論文の詳細を見る

• Reactive dilation of the epicardial coronary artery was measured after 20 sec coronary occlusion in 12 conscious dogs. The dogs were subjected to the implantation of a pair of ultrasonic crystals of 1-2mm in size, an ultrasonic flow-meter probe and a hydraulic occluder around the proximal left circumflex artery in the period from 7 to 10 days before the measurement. The percent difference of cross sectional area (%ΔCSA) of the artery between the maximal reactive dilation after reactive hyperemia and the control value was significantly correlated (r=0.49) to the peak flow rate of reactive hyperemia. When the experiment was limited to the cases with low CSA, the correlation was closer (r=0.66). The peak flow rate of reactive hyperemia was significantly correlated to the peak hyperemia time. But the %ΔCSA of reactive dilation was not correlated to the peak dilation time. The %ΔCSA was significantly attenuated by the administration of nitroglycerin (at 25μg/kg, 0.94±0.35 to 0.08 ±0.05%), diltiazem (at 0.3mg/kg, 1.64±0.65 to 0.32±0.18%) and dipyridamole (at 1 mg/kg, 0.78±0.36 to 0.07±0.04%). On the contrary, it was significantly augmented by the administration of ergonovine (at 0.4mg, 0.96±0.93 to 4.02±1.12%) and methoxamine (at 50μg/kg, 0.63±0.25 to 2.05±0.44%). The drugs in the former group except for nitroglycerin decreased the peak flow rate of reactive hyperemia, while those in the latter decreased the coronary dimension before reactive hyperemia. In this experiment %ΔCSA, peak flow rate and the time course of reactive dilation and hyperemia were not affected by the pharmacological denervation (propranolol 0.5 mg/kg+phentolamine 1mg/kg). Thus, the reactive dilation of the epicardial coronary artery was associated with an increase in coronary flow during reactive hyperemia and would be independent of the autonomic nervous control, suggesting the flow-dependent vasodilation mechanism. Further, it is suggested that vasotonus is an important factor for the reactive dilation because the dilation was augmented at a vasotonic or vasospastic state of the coronary artery.

• 近畿大学の論文
• 1989-03-25

著者

• 坂口 好秀

  近畿大学医学部第1内科学教室

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