Fig. 7.

Inhibitory effect of intraperitoneal injection of 2-APB on hypoxia-induced pulmonary hypertension (HPH) in mice. (a) Experimental protocol for the prevention experiment using 2-APB. Eight-week-old C57Bl/6 mice are subjected to normoxia (Nor, room air or 21% O₂) or hypoxia (10% O₂) for four weeks. 2-APB (1 mg/kg, q.d.) was intraperitoneally injected (i.p.) at the beginning of hypoxia exposure and continuously injected for four weeks during hypoxia. (b) Chemical structure of 2-APB. (c) Diagram showing that 2-APB blocks Ca²⁺ (or Na₊) influx through a receptor-operated cation channel. (c) Representative records of right ventricular pressure (RVP) (upper panels) and RV contractility (RV ± dP/dt) (lower panels) in normoxic (Nor) mice, hypoxic (Hyp) mice and Hyp mice receiving 2-APB (1 mg/kg, i.p., q.d., for two weeks after four weeks of hypoxia exposure). (d) Summarized data (mean ± SE, n = 5) showing RV systolic (RVSP), estimated mean pulmonary arterial pressure (mPAP), RV ± dP/dt_max, RV contractility index (RV ± dP/dt_max/RVSP) and heart rate in Nor, Hyp and Hyp+2-APB mice. ***p < 0.001 vs. Nor; ^###p < 0.001 vs. Hyp (one-way ANOVA). (e) Representative angiography images of the left lung at 8× (upper panels) and 30× (lower panels) magnification from Nor, Hyp, and Hyp+2-APB mice. (f) Summarized data (mean ± SE, n = 5) showing the total length of lung vascular branches(left panel), the number of lung vascular branches (middle panel) and the number of lung vascular branch junctions (right panel) per square millimeter of the selected peripheral lung area from Nor, Hyp, and Hyp+2-APB mice. ***p < 0.001 vs. Nor; ^##p < 0.01, ^###p < 0.001 vs. Hyp (one-way ANOVA).