ペンシル型CCD 生体顕微鏡システムを用いたin vivo肺微小循環と肺胞呼吸の同時可視化

We succeeded in visualizing in vivo perialveolar microcirculation and individual alveolar respiration in rats,by our high resolution intravital charge-coupled device videomicroscopy system. To elucidate the relevance and usefullness of our methods, we investigated their behavior 1) under control conditions, 2) during increased tidal volumes (TV), 3)during positive-end expiratory pressure (PEEP) application, and 4)during exposure to hypoxia. We recognized a sheet-like flow pattern in capillaries, and observed semi-collapsed capillaries at end-inspiration while flow continued.The latter indicate existence of“vascular waterfall phenomenon”.When TV was increased from 2.5 to 5ml, the alveolar size was increased from 30±10 to 65±18μm (n＝21, p＜0.05), and the red blood cell velocities in perialveolar capillary were significantly decreased from 910±210 to 290±140μm/sec (n＝21,p＜0.05). Following PEEP application with TV of 5ml,the alveolar diameter was increased even more to 80±20μm (n＝12,p＜0.05)and the flows of microvessels stopped temporarily at end-inspiration.We also visualized that precapillary arterioles clearly constricted from 34±6 to 28±6μm in response to hypoxia (n＝9, p＜0.05). In conclusion, the intravital pencil lens-probe videomicroscopy can be a powerful tool for in vivo observation of perialveolar microcirculation and alveolar respiration under important physiological conditions such as changing TV, application of PEEP, and exposure to hypoxia.

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