In Vivo, Visualization study of Vasoreactivity and morphology of Perialveolar Microcirculation in Rats with Pulmonary Hypertension

Abstract

[0bjective] To visualize in vivo perialveolar microcirculation in pulmomary hypertension rats with our novel CCD videomicroscopy to evaluate their vasoreactivity together with their morphological damage. [Method] We visualized in vivo perialveolar microcirculations in monocrotaline(MCT) treated rats with our novel pencil-lens CCD videomicroscopy and evaluated their possible altered morphology and vasoreactivity by endothelium-dependent vasodilator, acetylcholine(2μg/kg/min). The morphology of arterioles were studied by the injection of metacrylate resin into the pulmonary artery and visualized by scanning electron microscopy. [Results] Pulmonary arterial pressure were 22±3 under control, 37±8 at 1w, 42±4 at 2w, 64±22 mmHg at 3w after MCT administration. The morphology of arterioles exhibited a serpentine configuration with rough and uneven inner surface. Capillaries of PH also exhibited deformed morphology with apparently less vascular volume. The endothelial dependent vascular reactivity of pulmonary arterioles was reduced at 3w after MCT administration(10.6±11.0, 9.0±7.5, 3.0±7.0mmHg). [Conclusion] The pulmonary arterioles reactivity to Ach was reduced in MCT rats with arteriolar morphological changes, indicating endotherial dysfunction with remodeling occurs when PH exists. [Jpn J Physiol 54 Suppl:S112 (2004)]