AJP - Renal Physiology, Vol 248, Issue 2 314-F318, Copyright © 1985 by American Physiological Society
An improved bioassay method for determining natriuretic activity of atrial extracts
M. D. Johnson
Extracts of mammalian atrial tissue contain potent natriuretic substances
known collectively as atrial natriuretic factor (ANF). The purposes of the
present experiments were: 1) to improve on existing bioassay methodology
for the detection of ANF activity in atrial extracts, and 2) to compare the
ANF activity of atrial extracts prepared from Brattleboro-stain diabetes
insipidus (DI) rats with that from normal and water-deprived Long-Evans
(LE) rats. A pool of atrial tissue extract (AE) was prepared from normal
Sprague-Dawley rats for use as a standard against which unknown AE samples
could be compared. Five doses, ranging from 27 to 432 micrograms of AE
protein, were assayed in the Sprague-Dawley bioassay rats.
Phosphate-buffered saline (PBS) vehicle and ventricular tissue extracts
were also assayed. Statistical analysis of several log dose-response
relationships revealed that the bioassay response most appropriate in
determining relative natriuretic activity of AE was the log of the
experimental/control ratio for sodium excretion. The bioassay was used to
demonstrate that PBS atrial extracts from both water-deprived LE rats and
DI rats contain more natriuretic activity than do PBS atrial extracts from
LE rats.
