AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 4 750-R752, Copyright © 1984 by American Physiological Society
Synthesis and renal activity of rat atrial granules depend on extracellular volume
U. Ackermann and T. G. Irizawa
Extracellular fluid volume (by 22Na) and extent of 4-h [3H]fucose
incorporation into atrial-specific granules were measured in
deoxycorticosterone acetate (DOCA)/salt-loaded or Na-deficient rats. The
natriuretic potency of extracts from their atria was also measured in assay
rats. DOCA/salt-treated animals had a significantly greater extracellular
volume, a significantly greater degree of fucose uptake, and a
significantly more potent diuretic and natriuretic effect than did
Na-deficient rats. These observations, together with the known decrease in
atrial granularity with DOCA treatment, suggest that a chronic increase in
extracellular fluid volume is associated with increased synthesis and
metabolism of atrial natriuretic factor. They also confirm the finding
reported by others that granularity and natriuretic potency are not always
directly related. It may be that visible granules represent a peptide
storage form that requires further processing to become natriuretic.
