Endothelin-B receptors on suprachoroidal melanocytes mediate an endothelin-1-induced increase in the intracellular calcium concentration of rabbit ocular suprachoroidal tissue.
The physiological properties of endothelin-1 in ocular choroidal melanocytes are not well-known, although endothelin-1 increases the intracellular calcium concentration through endothelin-B receptors in skin melanocytes. We studied the effect of endothelin-1 on choroidal melanocytes in rabbit ocular suprachoroidal tissue. Fura-2 microfluorophotometry indicated that endothelin-1 and endothelin-B receptor selective agonists, endothelin-3 and BQ3020, increased the intracellular calcium concentration of the tissue. Endothelin-B receptor selective antagonist BQ788 blunted the response. Immuno-electron microscopy showed that endothelin-B receptor-like immunoreactivity was located only on melanocytes. These results indicate that endothelin-1 increases intracellular calcium concentration in rabbit suprachoroidal tissue via endothelin-B receptors on melanocytes.
Hirose
Akira
A
Department of Ophthalmology and Visual Science, Graduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan. Hiroseakira@aol.com
Azuma
Hiroshi
H
Tokoro
Takashi
T
Hirai
Keiji
K
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002829:Choroid / Q000166:cytology*; D003592:Cytophotometry; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology*; D019334:Endothelin-3 / Q000494:pharmacology; D016232:Endothelins / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D007124:Immunoenzyme Techniques; D008297:Male; D008544:Melanocytes / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011817:Rabbits; D044023:Receptor, Endothelin B / Q000819:agonists / Q000378:metabolism*
D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D019334:Endothelin-3; D016232:Endothelins; D005456:Fluorescent Dyes; D009842:Oligopeptides; D010446:Peptide Fragments; D010880:Piperidines; D044023:Receptor, Endothelin B; C075771:BQ 3020; C086539:BQ 788; D002118:Calcium; D016257:Fura-2