ISSN:
1432-0878
Keywords:
Atrial myoendocrine cells
;
Morphometry
;
Plasma atrial natriuretic peptides
;
Circadian variations
;
Rat (Wistar)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Subcellular structures of atrial myoendocrine cells in the rat heart and plasma concentrations of atrial natriuretic peptides (ANP) were examined at six evenlyspaced time points over 24 h, using morphometric techniques and radioimmunoassay. Myofibrils and mitochondria of the cells occupied 73.3% of the cytoplasm; 2% of the cytoplasm was occupied by secretory granules, rough endoplasmic reticulum and Golgi complexes, structures characteristic of endocrine cells. Plasma ANP concentration was maximal at 08.00 h, when the individual volume of secretory granules was minimal. The numerical density of secretory granules was increased at 12.00 h. The plasma ANP concentration was minimal at 20.00 h, when the numerical density was minimal and the individual volume was maximal. The fluctuation in plasma ANP concentrations over 24 h was thus parallel to that in the numerical densities of secretory granules and inverse to that in individual volumes. These results suggest that in rats the secretory activity of atrial myoendocrine cells increases at the beginning of the resting period, whereas it decreases at the beginning of the active phase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00220026
