The pH of mitochondria of fibroblasts from a hyperornithinaemia, hyperammonaemia, homocitrullinuria‐syndrome patient

The intracellular pH of control fibroblasts and of fibroblasts of a HHH‐syndrome patient have been determined. Values of 6.94±0.15 and 7.05±0.14 for control and patient fibroblasts, respectively, were found. By means of analyses of malate in the cytosolic and particulate fractions of the fibroblasts the differences in pH between these two cellular compartments were estimated to be 1.34±0.12 and 1.38±0.18 for control and patient, respectively. Neither difference was statistically significant. The decrease in the rate of ornithine uptake by mitochondria of the patient's fibroblast is therefore not due to an increased intramitochondrial pH.