Adrenal capillary endothelial cells stimulate aldosterone release through a protein that is distinct from endothelin.
We tested the possibility that bovine adrenal capillary endothelial cells (ECs) stimulate aldosterone secretion from bovine zona glomerulosa (ZG) cells by the release of a transferable factor. In coincubations of ZG cells and ECs in serum-free medium, aldosterone release was stimulated approximately 17-fold, and the stimulation was related to the concentration of ECs. The maximal stimulation by ECs was 75% of the maximal response to ACTH. In contrast, adrenal pericytes and fibroblasts were without effect. ECs incubated alone without ZG cells did not produce aldosterone. Conditioned medium from ECs (EC-CM), but not adrenal fibroblasts, stimulated aldosterone release approximately 3-fold. The stimulation increased with the concentration of EC-CM and the duration of conditioning time. Steroidogenic activity in EC-CM was abolished by pronase treatment, indicating that the active factor was a protein. However, the activity in EC-CM was distinct from that of endothelin-1 (ET-1), an endothelial peptide that also stimulates aldosterone secretion, as it was not blocked by the ET(B) receptor antagonist PD-145065, it did not alter [125I]ET-1 binding to ZG cells, and its release occurred before the release of ET-1. Neither ECs nor EC-CM stimulated the production of cortisol from zona fasciculata cells. The activity of EC-CM was not blocked by an angiotensin II AT1 receptor antagonist or a bradykinin B2 receptor antagonist. EC-CM stimulated increased intracellular calcium in fura-2-loaded ZG cells, but did not increase the production of cAMP. Using gel filtration, this peptide had an approximate molecular mass of 3000 Da and migrated earlier than ET-1. This study demonstrates that ECs in vitro alter steroidogenesis through the release of a transferable substance and suggests the existence of an endothelium-derived steroidogenic factor that is produced by adrenal capillary ECs. This endothelium-derived steroidogenic factor may function in the adrenal gland as a paracrine regulator of aldosterone secretion.
Rosolowsky
L J
LJ
Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee 53226, USA.
Hanke
C J
CJ
Campbell
W B
WB
D000311:Adrenal Glands / Q000098:blood supply*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000450:Aldosterone / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002196:Capillaries / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D002417:Cattle; D018920:Coculture Techniques; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D006727:Hormone Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D009994:Osmolar Concentration; D011402:Pronase / Q000494:pharmacology; D044023:Receptor, Endothelin B; D013256:Steroids / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D013997:Time Factors; D015383:Zona Fasciculata / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D015384:Zona Glomerulosa / Q000166:cytology / Q000187:drug effects / Q000502:physiology
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D006727:Hormone Antagonists; D009842:Oligopeptides; D044023:Receptor, Endothelin B; D013256:Steroids; D000804:Angiotensin II; C082887:PD 145065; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D011402:Pronase; D001920:Bradykinin