Cerebral salt wasting in subarachnoid hemorrhage rats: model, mechanism, and tool.

Cerebral salt wasting (CSW) frequently occurs concomitantly with aneurysmal subarachnoid hemorrhage (SAH). CSW induces excessive natriuresis and osmotic diuresis, and reduces total blood volume. As a result, the risk of symptomatic cerebral vasospasm may be elevated. Therefore, it is important to determine the mechanism of CSW. The purpose of this study was to evaluate whether the rat SAH model exhibits CSW and to investigate the relationship between CSW and natriuretic peptides. A SAH model was produced in 24 rats by perforating a cerebral artery with a nylon thread up through the common carotid artery. To evaluate CSW, urine was cumulatively collected from SAH onset to 12 hours and sodium (Na) excretion was analyzed. Body weight and hematocrit were analyzed before and after SAH onset. Concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in plasma were also analyzed. Urine volume and total Na excretion of SAH rats were significantly higher than those of sham rats (p<0.05). Body weight of SAH rats significantly decreased and hematocrit significantly increased (p < 0.05). ANP concentration was significantly decreased in SAH rats (p<0.05). However, BNP concentrations did not change. This study demonstrated for the first time that a rat SAH model exhibited CSW. It was suggested that the cause of CSW was neither ANP nor BNP. In addition, this rat SAH model will be useful for study of CSW after SAH.