Pulmonary vascular remodeling in broiler and Leghorn chickens after unilateral pulmonary artery occlusion.

Morphological and physiological responses to unilateral pulmonary artery occlusion (PAO) were evaluated in male broiler (B) and Leghorn (L) chickens. All birds were fed a diet containing 3,200 kcal of ME/kg of feed and 23% CP. Broilers (18-21 d old; 507 ± 40 g of BW) and L (61-64 d old, 861 ± 87 g of BW) had surgical PAO (n = 40 each strain) or were sham-operated (SHAM; n = 40 each strain). Hematocrit (%, Hc), relative lung weight (wet right + left lung weight/BW × 100), right ventricle to total ventricle weight ratio (RV/TV), and resistance pulmonary arterioles (RPA) thickness were measured in 6 chickens per group one day presurgery, and at 7 and 14 d postsurgery. Data were analyzed using one-way ANOVA. Relative lung weight was higher in L-chickens than in B-chickens at all sampling times. There were no differences in Hc between B and L presurgery, but at d 7 and 14, L-PAO chickens had the highest Hc (35 ± 1.4 and 40 ± 1.9, respectively); the B-SHAM had a lower Hc (28 ± 1.2, and 29 ± 1.0) than the L-SHAM (32 ± 1.2 and 34 ± 1.1) and the B-PAO (32 ± 1.2 and 34 ± 2.0) chickens, with no differences between L-SHAM and B-PAO. The RV/TV ratio was highest in the B-PAO at d 7 and d 14, with no differences among the other groups. The B-PAO chickens had the thickest RPA at 7 d and 14 d postsurgery than the rest of the groups, whereas B had thicker RPA than L at presurgery. Broilers had a lower ventilation capacity than L, and after PAO they developed right ventricular hypertrophy and small arteriole remodeling, whereas the L-PAO showed a higher degree of hypoxemia (high Hct), but without changes in RV/TV ratios or small arterial remodeling, suggesting that L-chickens had a better pulmonary arterial vasodilation even after chronic increases in blood flow through a single lung.