R. (1979). Aust. Paediatr. J., 15,[184][185][186] The Effect of cranial irradiation on blood-brain barrier permeability to methotrexate. Methotrexate (MTX) was given orally (30 mglm*) to 14 patients with leukaemiallymphoma before and soon after cranial irradiation (CI). The MTX levels in plasma and cerebrospinal fluid were measured three hours after the administration of MTX. Markedly increased blood-brain barrier (BBB) permeability of MTX was found in both asymptomatic and symptomatic patients with central nervous system (CNS) disease even before CI. Successful treatment of the CNS disease decreased the EBB permeability to MTX. CI per se did not increase the EBB permeability.

SUMMARY.Erythrocytes maintained in vitro under controlled conditions at pH 7·40 were unable to respond to changes in extracellular phosphate concentrations with changes in intracellular 2,3-bisphosphoglycerate content over an 8 h incubation period. Increased extracellular phosphate concentrations did not retard the rate at which 2,3-bisphosphoglycerate concentrations fell when erythrocytes were incubated at pH 7·10. Elevated extracellular phosphate concentrations did not increase the rate of recovery of intracellular 2,3-bisphosphoglycerate concentrations when erythrocytes were returned to pH 7·40 having been incubated at pH 7·10. The rate at which 2,3-bisphosphoglycerate concentrations increased under these latter conditions was too slow to counterbalance any effect that adjustment of blood pH may have on the position of the haemoglobin-oxygen dissociation curve during treatment of diabetic ketoacidosis.

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