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Angiotensin II receptors on human fetal adrenal cells
W E Rainey1, I M Bird, J I Mason
1Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas 75235-9032.
Objective:
Our objective was to determine if angiotensin II receptors are present on adrenal cells isolated from the human fetal zone and neocortex and to investigate if angiotensin II affects steroid production by these cells.
Study Design:
Primary cultures of both fetal zone and neocortex cells were prepared from fetal adrenal glands. Experiments were conducted to examine the binding of radiolabeled angiotensin II, angiotensin II activation of phospholipase C, and angiotensin II effects on steroidogenesis.
Results:
The majority of angiotensin II binding sites were of the type 1 subtype, as determined by displacement of radiolabeled angiotensin with specific receptor antagonists. Angiotensin II caused an increase in tritiated inositol phosphate accumulation in both neocortex and fetal zone cells. This increase could be blocked by type 1 angiotensin II receptor antagonists. Angiotensin II stimulated the production of cortisol, dehydroepiandrosterone, and dehydroepiandrosterone sulfate production during treatment for 2 days. The stimulation by angiotensin II, however, was substantially less than that seen in response to corticotropin treatment.
Conclusions:
The human fetal adrenal gland contains type 1 angiotensin II receptors early in gestation. The number of these receptors, albeit low, is sufficient to activate inositol phosphate production and steroidogenesis.