Determination of bufalin-like immunoreactivity in serum of humans and rats by time-resolved fluoroimmunoassay for using a monoclonal antibody.
The existence of a mammalian natriuretic substance or endogenous digitalis-like factor, which inhibits Na+,K+-ATPase and thereby regulates body fluid volume, has been speculated for a long time but has yet to be defined. We established in the present study a simple and highly sensitive procedure to measure bufalin, a constituent of toad venom preparation and a specific inhibitor of Na+,K+-ATPase by time-resolved fluoroimmunoassay (TR-FIA) and using a monoclonal antibody. The antibody was specific to bufalin and resembled bufadienolides but showed no cross-reactivity with digitoxin and ouabain. A bufalin-like immunoreactivity was detectable in serum of humans and rats by the proposed TR-FIA. The levels of bufalin-like immunoreactivity in serum of healthy volunteers were significantly correlated with their systolic blood pressure. Moreover, bufalin-like immunoreactivity in serum of Dahl-S rats increased in parallel with a period of high-salt diet. These results suggest that increased bufalin-like immunoreactivity may be associated with certain types of hypertension.
Department of Biochemical Toxicology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
M
M
Oda
M
M
Kurosawa
S
S
Numazawa
S
S
Tanaka
T
T
Akizawa
K
K
Ito
M
M
Maeda
T
T
Yoshida
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D002018:Bufanolides / Q000097:blood*; D003429:Cross Reactions; D015200:Fluoroimmunoassay; D006801:Humans; D008297:Male; D051381:Rats; D020303:Rats, Inbred Dahl
D000911:Antibodies, Monoclonal; D002018:Bufanolides; C022777:bufalin