Effect of atrial natriuretic peptide on ischaemic brain oedema

We investigated the effect of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium and potassium contents in ischaemic brain oedema. Global ischaemia (15 min) followed by recirculation (30 min) produced by a three vessel occlusion in the rat served as a model for induction of ischaemic cerebral oedema. Water content was measured by a drying-weighing method. Sodium and potassium contents were measured by means of flame photometry. The effect of ANP was evaluated by comparing these parameters of the ANP-treated group (5 micrograms/kg and 10 micrograms/kg atriopeptin) with those of the control group (administration of 0.9% NaCL). ANP did not significantly change the content of water, sodium and potassium in the preischaemic or ischaemic brain. Intraventricularly administered ANP (5 micrograms/kg and 10 micrograms/kg) caused significant decrease in the brain water (p less than 0.02) and sodium (p less than 0.01) contents after 15 min of ischaemia and 30 min of recirculation, while the brain potassium content remained unaltered. Serum osmolality, and sodium and potassium concentrations were not influenced by administration of ANP. Accordingly, ANP acts directly on the central nervous system to inhibit brain water and sodium accumulation in ischaemic brain oedema.