C-type natriuretic peptide in the human central nervous system: distribution and molecular form.

The distribution and molecular form of C-type natriuretic peptide (CNP) in the human central nervous system were studied with a specific radioimmunoassay for CNP-22. Immunoreactive (IR-) CNP was detectable in all regions of the brain examined (cerebral cortex, thalamus, hypothalamus, pons, and cerebellum) (0.21-0.81 pmol/g wet tissue, n = 4). The highest concentration of IR-CNP was found in the spinal cord at 1.83 +/- 0.13 pmol/g wet tissue (mean +/- SD, n = 3). Reversed-phase high performance liquid chromatography revealed a major peak migrating at the position corresponding to synthetic human CNP-53 and minor peaks comigrating with synthetic CNP-22 and the methionine-oxidized form of CNP-22, respectively. These findings suggest that IR-CNP is widely present in the human central nervous system mainly in a high molecular weight form as the major component and in the molecular form of CNP-22 as the minor component.