Intracellular pH of isolated perfused turtle heart

Abstract
Hearts from 15 painted turtles (Chrysemys picta) were perfused for 30 minutes at 23°–26°C with a buffered salt solution. The pH of the perfusing solution was varied between 6.5 and 9.5. The intracellular pH values of the ventricles were calculated from the distribution of the weak acid, 5.5-dimethyl-2,4-oxazolidinedione (DMO). It was found that the extracellular pH (pHe) and the intracellular pH (pHi) under these conditions could be related by the equation: pHi = 0.617 pHe + 2.98.