piperidines and phenidone

Endothelins (ETs) are a family of 21-amino acid hypertensive peptides, which together with their receptors ETA and ETB are expressed in human adrenal cortex. Evidence has been provided that ETs exert a potent secretagogue effect on human adrenocortical cells, acting through both ETA and ETB receptors. Therefore, it seemed worthwhile to study the signaling cascades mediating the cortisol secretagogue effect of the two receptor subtypes. Normal adrenal glands were obtained from consenting patients undergoing unilateral nephrectomy with ipsilateral adrenalectomy for renal cancer. Dispersed zona fasciculata-reticularis (ZF/R) cells were obtained by collagenase digestion and mechanical disaggregation. The selective activation of ETA and ETB receptors was obtained by exposing dispersed cells to ET-1 plus the ETB receptor antagonist BQ-788 and to the selective ETB receptor agonist BQ-3020, respectively. ETA and ETB receptors about equally contributed to the cortisol response of dispersed ZF/R cells to ETs. The phospholipase (PL) C inhibitor U-73122 abolished ETA-mediated secretory response, but only partially prevented the ETB-mediated one. The phosphatidylinositol 3-kinase inhibitor wortmannin and the protein kinase (PK) C inhibitor calphostin-C significantly blunted the secretory responses ensuing from the activation of both receptor subtypes, while the Ca(2+)-channel blocker nifedipine was ineffective. The ETB receptor-, but not the ETA receptor-mediated cortisol response was partially reversed by the cyclooxygenase (COX) inhibitor indomethacin, which when added together with U-73122 abolished it. The inhibitors of adenylate cyclase, PKA, tyrosine kinase and lipoxygenase did not affect the secretory response to the activation of either receptor subtype. ETA-receptor activation raised inositol triphosphate (IP3) production from dispersed ZF/R cells, while ETB-receptor stimulation enhanced both IP3 and prostaglandin-E(2) production. Collectively, our findings indicate that ETs stimulate cortisol secretion from human ZF/R cells, acting through ETA receptors exclusively coupled with PLC/PKC-dependent pathway and ETB receptors coupled with both PLC/PKC- and COX-dependent cascades.

Topics: Adenine; Androstadienes; Cells, Cultured; Endothelin Receptor Antagonists; Endothelins; Enzyme Inhibitors; Estrenes; Flavonoids; Humans; Hydrocortisone; Indomethacin; Naphthalenes; Nifedipine; Oligopeptides; Peptides, Cyclic; Phosphoinositide-3 Kinase Inhibitors; Piperidines; Protein Kinase C; Pyrazoles; Pyrrolidinones; Receptors, Endothelin; Signal Transduction; Type C Phospholipases; Tyrphostins; Wortmannin; Zona Fasciculata; Zona Reticularis

The mechanisms and factors leading to enhanced aldosterone secretion and ultimately to neoplastic transformation of the adrenal cortex are poorly defined. Angiotensin-II (Ang-II) and endothelin-1 (ET-1) have emerged as likely candidates among potential aldosterone secretagogues and adrenocortical growth-promoting factors. We therefore compared the effects of Ang-II and ET-1 on steroid hormone secretion of Conn's adenomas.. Ten Conn's adenomas that showed responsiveness to Ang-II blockade in vivo were recruited. Fragments of the tumors were collected immediately after surgical excision, and dispersed cells were obtained by collagenase digestion and mechanical disaggregation. Steroid hormones secreted by dispersed Conn's adenoma cells were assayed by quantitative high-performance liquid chromatography or radioimmunoassay.. Both Ang-II and ET-1 (10(-9) mol/L) similarly enhanced the overall steroid hormone production. ET-1 raised the release of pregnenolone (as evaluated by blocking its further metabolism by cyanoketone), corticosterone, 18-hydroxycorticosterone, and aldosterone, without affecting that of 11-deoxycortisol, cortisol, and 11-deoxycorticosterone. The hormonal responses to ET-1 were partially reversed by 10(-7) mol/L of either the ETA-receptor antagonist BQ-123 or the ETB-receptor antagonist BQ-788 and were abolished when both antagonists were used together. The aldosterone response to the selective activation of ETA and ETB receptors was studied in three Conn's adenomas by exposing dispersed cells to ET-1 (10(-9) mol/L) plus BQ-788 (10(-7) mol/L) and to the ETB-receptor agonist BQ-3020 (10(-8) mol/L). Both treatments raised aldosterone output by about 2-fold. ETA receptor-mediated aldosterone response was abolished by the protein kinase (PK) C inhibitor calphostin C (10(-5) mol/L). ETB receptor-mediated secretory response was lowered by either calphostin C and the cyclooxygenase (COX) inhibitor indomethacin (10(-5) or 10(-4) mol/L) and was completely suppressed when these two were combined. The PKA inhibitor H-89 and the lipoxygenase inhibitor phenidone were ineffective.. Collectively, our findings indicate that Ang-II and ET-1 equipotently stimulate both early and late steps of aldosterone synthesis in Conn's adenoma cells. The secretagogue effect of ET-1 occurs via the activation of ETA and ETB receptors, which are coupled with the PKC-dependent and the PKC- and COX-dependent signaling pathways, respectively.

Topics: Adrenal Cortex Hormones; Adrenal Cortex Neoplasms; Adrenocortical Adenoma; Adult; Aged; Aldosterone; Angiotensin II; Endothelin-1; Endothelins; Female; Humans; Indomethacin; Isoquinolines; Male; Middle Aged; Naphthalenes; Oligopeptides; Peptide Fragments; Peptides, Cyclic; Piperidines; Prostaglandin-Endoperoxide Synthases; Protein Kinase C; Pyrazoles; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Signal Transduction; Sulfonamides; Tumor Cells, Cultured

Intravenous injection of arabinogalactan or dextran together with pontamine sky-blue dye into mice increased vascular permeability and led to marked blueing of the ears. Arabinogalactan caused a rapidly progressing ear blueing (maximal coloration 20-30 min after injection). This response was suppressed by pretreating the animals with the histamine H1-antihistamines levocabastine and loratadine. In contrast, dextran induced a slowly evolving ear inflammation (maximal coloration 60-90 min after injection), which was blocked by the 5-HT-serotonin antagonists cinanserin, metergoline and ritanserin. Furthermore, the dextran reaction was inhibited by the lipoxygenase (LO)/cyclooxygenase (CO) inhibitors BW540C, BW755C and phenidone and by the specific 5-LO inhibitor AA-861. Both arabinogalactan and dextran responses were inhibited by aprotinin, a kallikrein inhibitor, and the mixed H1/5-HT antagonists astemizole and azatadine. The inflammogenic activity of the polysaccharides was not affected by administration of the CO inhibitors indomethacin and suprofen, the thromboxane synthetase inhibitor dazoxiben, the H2-antihistamines cimetidine and ranitidine, the anticholinergics isopropamide or the PAF-antagonist L-652, 731. These data indicate the existence of distinctive endogenous molecules that mediate the pinnal extravasation reaction to both polysaccharides: histamine for arabinogalactan, serotonin and lipoxygenase-derived arachidonic acid metabolites for dextran.

Topics: 4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; Animals; Aprotinin; Astemizole; Benzimidazoles; Benzoquinones; Cinanserin; Cyproheptadine; Dextrans; Galactans; Histamine H1 Antagonists; Kinetics; Lipoxygenase Inhibitors; Male; Metergoline; Mice; Otitis; Piperidines; Pyrazoles; Quinones; Ritanserin; Serotonin Antagonists