Endogenous marinobufagenin-like factor in acute plasma volume expansion.
The aim of the study was to further investigate the nature of endogenous digitalis-like factors stimulated by acute plasma volume expansion (VE). 10 male Fisher 344XNB rats were given intravenous (iv) saline infusion (4% of the body mass) for 30 min, which caused a fall in % hematocrit (35.9+/-0.69 vs. 41.8+/-1.05; vs. 10 controls, P<0.01). EDLF was measured in C-18 reverse-phase extracted (32%+80% acetonitrile) tissues. VE was associated with an increase in plasma marinobufagenin-like factor (MLF)(0.49+/-0.05 vs. 0.2+/-0.06 nmol/L, P<0.01) and pituitary ouabain-like compound (OLC) (30.9+/-3.12 vs. 3.2+/-2.3 pmol/g, P<0.01). Plasma OLC decreased (0.087+/-0.018 vs. 0.21+/-0.04 nmol/L, P<0.02), and pituitary MLF did not change (0.05+/-0.01 vs. 0.07+/-0.02 pmol/g) after VE. Chloroform extracted urine from 5 volume-expanded male mongrel dogs was fractionated on reverse-phase HPLC columns in a linear gradient of 0-80% acetonitrile. The material cross-reacting with marinobufagenin antibody eluted from HPLC column as a single peak, demonstrated absorbance at 300 nm, and was distinct from ouabain-like material. Digoxin antibodies interacted with both marinobufagenin-like and ouabain-like immunoreactive material. These results provide further evidence for the presence of a bufodienolide EDLF in the mammals, and demonstrate that EDLF response to VE includes stimulation of brain OLC and plasma bufodienolide.
Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, MD 21224, USA.
O V
OV
Fedorova
P A
PA
Doris
A Y
AY
Bagrov
D000818:Animals; D001835:Body Weight; D001921:Brain / Q000378:metabolism; D002018:Bufanolides / Q000097:blood* / Q000302:isolation & purification / Q000652:urine; D002298:Cardenolides; D002851:Chromatography, High Pressure Liquid; D004077:Digoxin; D004285:Dogs; D004791:Enzyme Inhibitors / Q000097:blood* / Q000302:isolation & purification / Q000652:urine; D007262:Infusions, Intravenous; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism; D010953:Plasma Volume; D051381:Rats; D011916:Rats, Inbred F344; D012503:Saponins / Q000097:blood; D012965:Sodium Chloride / Q000008:administration & dosage; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
D002018:Bufanolides; D002298:Cardenolides; D004791:Enzyme Inhibitors; D012503:Saponins; C034504:digoxin-like factors; C093896:marinobufagenin; D012965:Sodium Chloride; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase