Fluid loading in rats increases serum brain natriuretic peptide concentration

Hyponatremia after subarachnoid hemorrhage has been linked to high plasma c oncentration of atrial natriuretic peptide and brain natriuretic peptide. V olume expansion therapy to prevent symptomatic vasospasm, such as intensive hypertensive and hypervoremic therapy, may alter systemic concentration of these peptides. We therefore examine brain natriuretic peptide secretion i n rats in response to acute volume expansion, infusing to 10 ml of saline o ver 1 h. In the 70 ml group, brain natriuretic peptide concentrations showe d a significant increase from pre-infusion concentrations 7 h after initiat ion of infusion, but had begun to fall 7 h later. We suspect that high plas ma concentration of brain natriuretic peptide after subarachnoid hemorrhage is partly caused by hypervoremic therapy.