Ganglionic, spinal cord and hypothalamic atrial natriuretic factor: its distribution, origin and possible role in...

We report the occurrence of the atrial natriuretic factor (ANF) prohormone in the hypothalamus, spinal cord and sympathetic ganglia determined by measurement of immunoreactive ANF by two peptide-specific radio-immunoassays with antibodies against near-C-terminal and near-N-terminal portions of ANF prohormone. This suggests local ANF generation in neural structures. In spontaneously hypertensive rats (SHR) we found an elevated ANF-C content in all tissues along the pathway of increased efferent sympathetic outflow, which is present in this animal model. The ANF-N was augmented in SHR only in the hypothalamus. This indicates an overall increase of neural ANF in SHR. The reported neuroinhibitory function of increased neural ANF, however, was attenuated by a decrease in the number of some brain and peripheral ganglionic ANF binding sites in SHR. It remains to be determined whether the increased neural ANF in SHR is a primary phenomenon or a compensatory increase induced by high blood pressure.