Pulmonary vascular pressure profiles in broilers selected for susceptibility to pulmonary hypertension syndrome: Age and sex comparisons

• Published in: Poultry science 2010-09, Vol.89 (9), p.1815-1824
• Main Authors: Wideman, R.F. Jr, Eanes, M.L, Hamal, K.R, Anthony, N.B
• Format: Article
• Language: English
• Subjects: Aging - physiology; animal age; Animals; arteries; ascites; blood capillaries; blood flow; blood pressure; Blood Pressure - physiology; broiler chickens; Chickens; diameter; disease resistance; Female; gender differences; Genetic Predisposition to Disease; hypertension; Hypertension, Pulmonary - genetics; Hypertension, Pulmonary - veterinary; Male; pathogenesis; poultry diseases; Poultry Diseases - genetics; Poultry Diseases - metabolism; pulmonary arterial hypertension; pulmonary arterial pressure; Pulmonary Artery; pulmonary venous hypertension; reference standards; respiratory tract diseases; risk factors; Sex Characteristics; Vascular Resistance; vasoconstriction
• ISSN: 0032-5791; 1525-3171
• DOI: 10.3382/ps.2010-00754

Broilers that are susceptible to pulmonary hypertension syndrome (PHS, ascites) have an elevated pulmonary arterial pressure (PAP) when compared with PHS-resistant broilers. Two distinctly different syndromes, pulmonary arterial hypertension and pulmonary venous hypertension (PVH), both are associated with increases in PAP. Pulmonary arterial hypertension occurs when the right ventricle must elevate the PAP to overcome increased resistance to flow through restrictive pulmonary arterioles upstream from the pulmonary capillaries. In contrast, PVH is commonly caused by increased downstream (postcapillary) resistance. The sites of resistance to pulmonary blood flow are deduced by making contemporaneous measurements of the PAP and the wedge pressure (WP) and calculating the transpulmonary pressure gradient (TPG) (TPG = PAP - WP). We obtained PAP and WP values from 8-, 12-, 16-, 20-, and 24-wk-old anesthetized male and female broilers from a PHS-susceptible line. Pressures were recorded as a catheter was advanced through a wing vein to the pulmonary artery and onward until the WP was obtained. In addition to sex and age comparisons of vascular pressure gradients, the data also were pooled to obtain 3 cohorts for broilers having the lowest PAP values (n = 52; range: 12 to 22.9 mmHg), intermediate PAP values (n = 63; range: 23 to 32.9 mmHg), and highest PAP values (n = 62; range: 33 to 62 mmHg) independent of age or sex. Within each of the age, sex, and PAP cohort comparisons, broilers with elevated PAP consistently exhibited the hemodynamic characteristics of pulmonary arterial hypertension (elevated PAP and TPG combined with a normal WP) and not PVH (elevated PAP and WP combined with a normal or reduced TPG). Susceptibility to PHS can be attributed primarily to pulmonary arterial hypertension associated with increased precapillary (arteriole) resistance.