Immunoactive iso-ANP/BNP in plasma, tissues and atrial granules of the rat.
We have developed a specific radioimmunoassay (RIA) for iso-rANP(1-45)/rBNP(51-95) using antiserum produced against a peptide comprise of the first 20 amino acid sequence of this cardiac hormone. Using this RIA, we found that atria contained the highest amount of iso-rANP(1-45) (567.37 pmol/g) which is about 140-fold higher than ventricles (4.32 pmol/g). With the exception of the lung and kidney, all other tissues had negligible amounts. The plasma level was 1.4 fmol/ml and the only molecular form found was the 45 amino acid form. HPLC analysis of extracts of isolated, purified atrial granules revealed that, like atrial natriuretic peptide (ANP), iso-rANP/rBNP is also stored in these granules. However, while ANP is stored predominantly as pro-ANP(1-126) and cleaved during or after release, iso-ANP/BNP is stored as the 45 amino acid form and may be processed prior to storage in the granules.
Hira
G K
GK
Department of Biochemistry, Queen's University, Kingston, Canada.
Sarda
I R
IR
Wong
S T
ST
Pang
S C
SC
Flynn
T G
TG
D000595:Amino Acid Sequence; D000818:Animals; D000937:Antigen-Antibody Reactions; D009320:Atrial Natriuretic Factor / Q000032:analysis* / Q000097:blood* / Q000276:immunology; D003594:Cytoplasmic Granules / Q000737:chemistry*; D006325:Heart Atria / Q000737:chemistry; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000097:blood* / Q000276:immunology; D011817:Rabbits; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley
D009419:Nerve Tissue Proteins; D020097:Natriuretic Peptide, Brain; C062794:iso-atrial natriuretic peptide; D009320:Atrial Natriuretic Factor