Pulmonary arteriole remodeling in hypoxic broilers expressing different amounts of endothelial nitric oxide synthase

Lung samples from 30 pulmonary hypertensive chickens expressing low nitric oxide (NO) synthase activity in endothelial arteriolar cells were compared with samples taken from 30 nonhypertensive animals expressing high activity to investigate a possible relationship between the just-mentioned expressions and pulmonary vascular remodeling. The external diameter and media muscular thickness in 20 arterioles of 50- to 200-microm external diameter were measured in lung samples from 17-, 30-, and 42-d-old broilers to calculate %T (medial wall width divided by external vessel diameter x 100). The %T was higher in hypertensive chickens than in nonhypertensive (P < 0.01) chickens and was inversely related to NO synthase enzyme (P < 0.01). It can be inferred from this study that NO is involved in the remodeling process in broilers with hypoxic pulmonary hypertension syndrome.