Fig. 1.
Long-term high-altitude hypoxia (LTH) results in a unique contractile response to bradykinin. Dose-response curves of pulmonary arterial rings exposed to 10 pM to1 μM bradykinin in an additive manner normalized to maximum 10 µM phenylephrine (PE)-precontracted tension (%T10 μM PE) for normoxic (filled circles) and LTH (open circles) sheep, comparing all normoxic and hypoxic control data (A), the normoxic dose-response curve with the hypoxic curve representative of arteries that contracted in response to bradykinin (C), and the normoxic curve with the hypoxic curve representative of arteries that did not contract in response to bradykinin (D). B: comparison of the percentage of total normoxic and LTH control pulmonary arterial rings that contracted in response to treatment with bradykinin. Lines show resultant fits with a Hill equation to the dose-response relationships, and markers show means ± SE. The dose-response data were analyzed by 2-way analysis of variance with a Bonferroni posttest analysis for each dose, and the difference in percentages was analyzed using a Chi-squared contingency test. **P < 0.01 and ***P < 0.001, statistical significance between normoxic and hypoxic groups. Normoxic, n = 11/40; LTH animals, n = 16/28.