Real-time pH and pCO2 monitoring of isolated rabbit aorta with microsensor system based on ion-sensitive field effect transistor

Abstract

Background: While acidification rate of tissues reflects global metabolism, utility of this characterization has been hampered by the need for precise and real-time measurements of a small quantity of solution. Therefore, we developed real-time pH microsensor system based on ion-sensitive field effect transistor (ISFET) which can detect pH change in less than 1 μL solution. We measured pH change and evaluate the fraction of CO₂ contribution to acidification of isolated rabbit aorta.Methods: The dimension of ISFET sensor was 0.45 mm width x 0.18 mm thickness x 5.5 mm length. Two sensors were placed at the center of isolated rabbit aorta (diameter: ~3 mm, n = 10) and one of these sensors were covered with silicon tube to assess pH change with CO₂. After 1 min continuous delivery of Tyrode solution buffered with sodium bicarbonate (pH 7.4), measurements were performed for ten min with the solution kept still at 37°C.Results: pH was decreased monotonically and saturated at ~10 min. the value of pH changes at ten min was –1.05 ± 0.42. The percentage of CO₂ contribution to the change of pH was 79.7 ± 6.1％.Conclusion: We firstly succeeded in real-time measuring acidification rate and evaluating CO₂ contribution to the change of pH of isolated rabbit aorta with ISFET based microsensor system. This technique will be useful to investigate the metabolic state of isolated tissues or cultured cells. [Jpn J Physiol 54 Suppl:S236 (2004)]