Flaim S F, Ress R J, Mest S
Pharmacology. 1985;30(1):1-11. doi: 10.1159/000138043.
This study was conducted to determine if there is a difference in the calcium handling mechanism of the thoracic and abdominal aortic regions of the rabbit aorta. Isolated segments of aorta from both regions were studied in HEPES buffer at 37 degrees C and bubbled with 100% oxygen using identical procedures. Intracellular calcium levels were determined after segments had been exposed to 45Ca-labeled buffer during experimental procedures and subsequently washed with a 'quench' solution of zero calcium, 2 mM EGTA, and HEPES buffer, maintained at 0 degree C. The results suggest that the thoracic region is capable of taking up more calcium under resting conditions compared to the abdominal aorta. During stimulation with norepinephrine, both regions show significantly increased calcium influx rates after 10 min of exposure to the agonist, but only in the abdominal region is this effect maintained after 60 min of norepinephrine stimulation. Net (summation of calcium influx and efflux) intracellular calcium levels are significantly increased by norepinephrine in the thoracic but not in the abdominal aorta. Taken together, these data suggest that, compared to the thoracic aorta, the abdominal aorta may possess a more effective calcium efflux mechanism which may be able to fully compensate for the norepinephrine-stimulated increase in calcium influx.
本研究旨在确定兔主动脉胸段和腹段的钙处理机制是否存在差异。使用相同的程序，在37摄氏度的HEPES缓冲液中对来自两个区域的离体主动脉段进行研究，并通入100%氧气。在实验过程中，将主动脉段暴露于45Ca标记的缓冲液中，随后用零钙、2 mM EGTA和HEPES缓冲液组成的“淬灭”溶液（保持在0摄氏度）冲洗，然后测定细胞内钙水平。结果表明，与腹主动脉相比，胸段在静息条件下能够摄取更多的钙。在用去甲肾上腺素刺激时，两个区域在暴露于激动剂10分钟后钙内流速率均显著增加，但仅在腹段，去甲肾上腺素刺激60分钟后这种效应仍持续存在。去甲肾上腺素使胸主动脉的细胞内钙净水平（钙内流和外流的总和）显著增加，但腹主动脉则不然。综上所述，这些数据表明，与胸主动脉相比，腹主动脉可能具有更有效的钙外流机制，该机制可能能够完全补偿去甲肾上腺素刺激引起的钙内流增加。
