Presentation of an experimental method to induce in vitro (“organ chambers”) respiratory acidosis and its effect on vascular reactivity

Abstract

PURPOSE: To create in vitro a model to generate acidosis by CO 2 bubbling “organ chambers”, which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity. METHODS: Eighteen male Wistar rats (230-280g) were housed, before the experiments, under standard laboratory conditions (12h light/ dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO 2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO 2) and pure CO 2. RESULTS: 1) 100% CO 2, pH variation very fast, pH minimum 6.0; 2) 90%CO 2 pH variation bit slower, pH minimum6.31; 3) 70%CO 2, pH variation slower, pH minimum 6.32; 4) 50% CO 2, pH variation slower, pH minimum 6:42; 5) 40%CO 2, Adequate record, pH minimum 6.61, and; 6) 30%CO 2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO 2 40%) was adopted. CONCLUSION: This gas mixture (O2 60% + CO 2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force.