The existence of low concentrations of atrial natriuretic peptide (ANP) in canine cerebrospinal fluid which does not correlate with plasma ANP levels

Atrial natriuretic peptide (ANP) concentrations in the cerebrospinal fluid (CSF) and plasma of canine were 2.1 +/- 1.1 pg/ml (mean +/- S.D.) and 53.1 +/- 21.1 (n = 20), respectively. The regression coefficient between these concentrations was -0.0045 (P = n.s.). The ANP concentration in the CSF did not change even after the plasma ANP concentration was altered following the change of left atrial pressure, as in 4 cases of an experimental aortic regurgitation. Thus, ANP concentration in the CSF is not influenced by ANP concentrations in the plasma at least under our condition. Gel permeation chromatography revealed a single form of ANP in the position of authentic alpha-ANP in canine CSF, while a high molecular weight ANP peak was observed as well as alpha-ANP in the plasma.