[The role of endothelin the development of hypoxic pulmonary hypertension]

To evaluate the role of endothelin in the development of hypoxic pulmonary hypertension, seven pigs (50 +/- 5kg) models with hypoxia induced pulmonary hypertension were established. Swan-Ganz catheter and arterial catheter were inserted into the pulmonary artery and aorta, pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO) and arterial blood gases were monitored before and during hypoxia and 5 min, 30 min, 60 min, 120 min after nitrendipine injected (100 micrograms/kg). Plasma endothelin concentration was measured by RIA. It was found that plasma ET concentration was significantly increased, from 5.5 +/- 1.1 ng/L during normoxia to 11.9 +/- 1.2 ng/L during hypoxia (PaO2 = 5.55 +/- 0.24 kPa) (P < 0.002), while PAP increased from 3.88 +/- 0.10 kPa to 5.92 +/- 0.19 kPa. After nitrendipine injection, PAP and ET level were decreased by 1.03 kPa (P < 0.05) and 40% (P < 0.02) respectively compared with those with pure hypoxia. Our results indicate that ET may play an important role in the development of hypoxia induced pulmonary hypertension. Ca++-channel blocker nitrendipine not only relieves hypoxic pulmonary hypertension, but also inhibits the release of endothelin.