AJP - Endocrinology and Metabolism, Vol 259, Issue 2 E246-E255, Copyright © 1990 by American Physiological Society
Brain natriuretic peptide binding sites in rats: in vitro autoradiographic study
E. M. Konrad, G. Thibault, S. Pelletier, J. Genest and M. Cantin
Laboratory of Pathobiology, Clinical Research Institute of Montreal, Quebec, Canada.
Brain natriuretic peptide (BNP) is a recently discovered family of
natriuretic peptides highly homologous to atrial natriuretic factor (ANF).
Quantitative in vitro autoradiography with a computerized microdensitometer
demonstrated that the distribution of BNP binding sites is similar to the
known distribution pattern of ANF binding sites in rat tissues. Analysis of
saturation and competition curves disclosed that the maximal binding
capacity for BNP-(Asp-81--Tyr-106) and ANF-(Ser-99--Tyr-126) is similar
within the plexiform layer of the olfactory bulb, the choroid plexus, and
the adrenal zona glomerulosa. Examination of the competition curves of
BNP-(Asp-81--Tyr-106), ANF-(Ser-99--Tyr-126), and
des-(Gln-116--Gly-120)ANF-(Asp-102--Cys-121)NH2 (C-ANF, a ligand highly
specific for ANF-R2 receptors) for 125I-labeled BNP-(Asp-81--Tyr-106) and
125I-labeled ANF-(Ser-99--Tyr-126) binding revealed that ANF fully
displaced 125I-BNP binding and, conversely, BNP completely displaced
125I-ANF binding in these tissues, whereas C-ANF partially displaced
125-BNP and 125-ANF binding. Angiotensin II, insulin, glucagon, and
substance P had no influence on 125I-BNP binding in the above tissues.
These results support the view that BNP and ANF share the same binding
sites in rats.
