Relationship between β‐Adrenergic Receptor Numbers and Physiological Responses during Experimental Canine Myocardial Ischemia
Relationship between β‐Adrenergic Receptor Numbers and Physiological Responses during Experimental Canine Myocardial Ischemia
复制标题
实验性犬心肌缺血期间β-肾上腺素能受体数量与生理反应的关系
作者：
A. Mukherjee;L. Bush;K. McCoy;R. Duke;H. Hagler;L. Buja;J. Willerson
在本研究中，我们评价了犬缺血心肌β-肾上腺素能受体数量增加对(−)-异丙肾上腺素和肾上腺素刺激的生理反应。在冠状动脉左前降支近端暂时阻断1小时后，在15分钟的复流期内，狗以足以增加心率20-40次/分钟的速度静脉注射(−)-异丙肾上腺素。在注入异丙肾上腺素后，从缺血区和非缺血区获取心肌组织，用于测量β-肾上腺素能受体数目、环磷酸腺苷含量和磷酸化酶b到a的转换。左心室(LV)缺血组织β-肾上腺素能受体数量显著增加。(−)-异丙肾上腺素的应用与左心室缺血组织中环磷酸腺苷含量和磷酸化b向a的转化显著增加有关。此外，给予(−)-肾上腺素显著增加了缺血组织中磷酸化酶b向非缺血组织的转化，这种转化可被(±)-心得安阻断。这些数据表明，在这个实验模型中，犬左室缺血组织中β-肾上腺素能受体的数量增加，当它们在体内被适当的激动剂激活时，能够翻译生理反应。
In the present study, we evaluated the physiological responsiveness of the increased numbers of β-adrenergic receptors in ischemic canine myocardium to in vivo stimulation by (−)- isoproterenol and epinephrine. After 1 hour of temporary proximal left anterior descending coronary artery occlusion and during a 15-minute period of reflow, dogs received (−)-isoproterenol intravenously at a rate sufficient to increase their heart rates 20–40 beats/min. Following the infusion of isoproterenol, myocardial tissue was obtained from the LV ischemic and nonischemic regions for measurement of β-adrenergic receptor numbers, cyclic AMP content, and phosphorylase b to a conversion. β-Adrenergic receptor numbers were significantly increased in the left ventricular (LV) ischemic tissue. The administration of (−)-isoproterenol was associated with significant increases in cyclic adenosine monophosphate content and phosphorylase b to a conversion in the LV ischemic tissue. Also, the administration of (−)-epinephrine significantly increased the phosphorylase b to a conversion in ischemic tissue over the nonischemic tissue and this conversion was blocked by pretreatment with (±)-propranolol. These data suggest that, in this experimental model, the increased numbers of β-adrenergic receptors in canine LV ischemic tissue are capable of translating physiological responses when they are activated with an appropriate agonist in vivo.