Fig. 3.

PH is prevented by administration of SB203580, a p38 MAPKα inhibitor. A and B: animals were exposed to a hypobaric hypoxic environment for 2 wk. Some animals received daily injections of SB203580. Hemodynamics (A) and hematocrit (B) were measured after 2 wk. RVSP, right ventricular (RV) systolic pressure. Data represent mean values ± SE. Total animals n = 5–6 per group. C: hearts were isolated from the animals and the RV was dissected out from the left ventricle (LV) and septum. The ventricles were dry blotted and then weighed, and the ratio was calculated. The total RV weight was also plotted. Values are means ± SD; n = 5 per group. **P < 0.05. D: noninvasive systemic blood pressure taken by tail-cuff measurement. E and F: rats were exposed to hypoxia ± SB203580. The lungs were removed after experiment and sections (5 mm) cut. These were stained with α-smooth muscle actin and the vessels <80 mm were analyzed for degree of muscularization. Five random fields per slide were analyzed with 3 slides per animal. The vessels were categorized as completely, partially, or nonmuscularized and are presented as numbers per total number of vessels present in each field. Groups analyzed by ANOVA for overall change with posttest analysis; n = 5 animals. ***P < 0.001, for A–C and E.