Rapid preparation of hypoxic Krebs-Henseleit solution with sodium sulfite for in vitro model of hypoxic pulmonary vasoconstriction

AIM: To investigate the feasibility of using sodium sulfite (Na₂SO₃) to prepare hypoxic Krebs-Henseleit (KH) solution for hypoxic pulmonary vasoconstriction (HPV) model in vitro. METHODS: Different doses of Na₂SO₃ were added into 0.5 L KH solution at 37°C. An i-STAT portable clinical analyzer was used to measure the oxygen partial pressure (PO₂), carbon dioxide partial pressure (PCO₂), pH value and the concentration of sodium (Na⁺) in these KH-Na₂SO₃ solutions 1 min after administration. Then the dose of Na₂SO₃ suitable for HPV model was dissolved in 0.5 L KH solution and the above indexes in the solution were monitored at various time points at 37°C under atmospheric pressure. RESULTS: More than 0.2 g (including 0.2 g) Na₂SO₃ reduced the PO₂ of 0.5 L KH solution in a dose-dependent manner (P<0.01). In addition, 1.5 g Na₂SO₃ reduced the PO₂ of 0.5 L KH solution to 20~40 mmHg and maintained the hypoxic state for at least 90 min (suitable for HPV model in vitro), but had nearly no effect on the PCO₂, pH and Na⁺ levels. CONCLUSION: The hypoxia solution for HPV model could be reached by Na₂SO₃ in open air and the method is simple, easily feasible and stable.