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This Article Full Text Full Text (PDF) All Versions of this Article: 296/6/L1042    most recent 90327.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Howell, K. Articles by McLoughlin, P. PubMed PubMed Citation Articles by Howell, K. Articles by McLoughlin, P.

L-Arginine promotes angiogenesis in the chronically hypoxic lung: a novel mechanism ameliorating pulmonary hypertension

School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Sciences, University College Dublin, Dublin, Ireland

Submitted 30 May 2008 ; accepted in final form 27 March 2009

Chronic alveolar hypoxia, whether due to residence at high altitude or lung disease, leads to a sustained increase in pulmonary vascular resistance and pulmonary hypertension (PH). Strategies that augment endogenous nitric oxide production or activity, including L-arginine supplementation, attenuate the development of PH. This action has been attributed to inhibition of vessel wall remodeling, thus preventing structural narrowing of the vascular lumen. However, more recent evidence suggests that structural changes are not responsible for the elevated vascular resistance observed in chronic hypoxic PH, calling into question the previous explanation for the action of L-arginine. We examined the effect of dietary L-arginine supplementation on pulmonary vasoconstriction, structurally determined maximum vascular lumen diameter, and vessel length in rats during 2 wk of exposure to hypoxia. L-Arginine attenuated the development of hypoxic PH by preventing increased arteriolar resistance. It did not alter mean maximal vascular lumen diameter, nor did it augment nitric oxide-mediated vasodilatation, in chronically hypoxic lungs. However, the total length of vessels within the gas exchange region of the hypoxic lungs was significantly increased after L-arginine supplementation. These findings suggest that dietary L-arginine ameliorated hypoxic PH, but not by an effect on the structurally determined lumen diameter of pulmonary blood vessels. L-Arginine enhanced angiogenesis in the hypoxic pulmonary circulation, which may attenuate hypoxic PH by producing new parallel vascular pathways through the lung.

vascular endothelial growth factor; nitric oxide; hypoxia; lung disease