Furosemide does not facilitate pulmonary vasodilation in broilers during chronic or acute unilateral pulmonary arterial occlusion

Furosemide (FURO) is a diuretic and a putative pulmonary vasodilator that, when added to broiler diets, previously has been shown to reduce the cumula tive pulmonary hypertension syndrome (PHS) mortality induced by cold temper atures. The objective of the present study was to evaluate the influence of dietary FURO on the pulmonary vasculature in broilers undergoing chronic o r acute unilateral pulmonary arterial occlusion. Broilers were fed a standa rd ration throughout the entire experiment (Control group) or the same rati on supplemented with 0.015% (wt/wt) FURO from Day 14 to 42 (FURO group). In the present study chicks were chosen at random at 16 to 18 d of age to und ergo sham surgery or a chronic unilateral pulmonary artery clamp (PAC) proc edure. Diet and surgical treatments resulted in Control-Sham, FURO-Sham, Co ntrol-PAC, and FURO-PAC groups. The Control-PAC and FURO-PAC groups did not differ in body weight or right:total ventricular weight ratios (RV:TV). Th e postsurgical mortality, ascites mortality, and mortality due to other cau ses did not differ between the Control-PAC and FURO-PAC groups. Plasma Na(P less than or equal to 0.05) was lower in the FURO-Sham group than in the Control-Sham group. Broilers from the same hatch were fed Control or FURO diets and surgically prepared for acute unilateral pulmonary arterial occlu sion by using a snare. Tightening of the snare triggered characteristic inc reases in pulmonary blood flow, pulmonary arterial pressure, and pulmonary vascular resistance. Across all of these variables, the Control and FURO gr oups did not differ during any sample interval. Dietary FURO did not affect body weight, hematocrit, or RV:TV. Dietary FURO at 0.015% (wt/wt) does not appear to influence the pulmonary vasculature in broilers, but it may prol ong the survival of broilers during the pathophysiological progression of P I-IS.