Hormonal stimulation of 12(R)-HETE, a cytochrome P450 arachidonic acid metabolite in the rabbit cornea.
12(R)-HETE [12(R)-hydroxy-5, 8, 10, 14 eicosatetraenoic acid] is one of the major arachidonic acid metabolites produced by microsomal cytochrome P450 of the corneal epithelium. This metabolite is a potent inhibitor of Na(+)-K(+)-ATPase activity in several tissues. We investigated endogenous production of 12(R)-HETE in the rabbit corneal epithelium. Incubation of corneal epithelial sheets (prelabeled with 14C-arachidonic acid) with arginine vasopressin resulted in the production of radioactive 12(R)-HETE suggesting its formation from endogenously labeled-arachidonic acid. The maximal response was obtained with 1 microM arginine vasopressin and represents a 15-fold increase in 12(R)-HETE formation compared with that of control tissues. Stimulation of 14C-arachidonic acid release with a detergent, digitonin, also resulted in endogenous 12(R)-HETE formation. Analysis of the incubation media following digitonin treatment of prelabeled corneal epithelial sheets revealed that 12(R)-HETE production was maximal at 20 microM digitonin, a 17-fold increase over control values. This study is the first to describe hormonal and traumatic stimulation of 12(R)-HETE formation from endogenously labeled arachidonic acid in intact corneal tissues. This study demonstrates that the formation of this Na(+)-K(+)-ATPase inhibitor can be modulated by physiological and pathophysiological regulation.
Davis
K L
KL
Department of Pharmacology, New York Medical College, Valhalla.
Dunn
M W
MW
Schwartzman
M L
ML
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D001127:Arginine Vasopressin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003315:Cornea / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004072:Digitonin / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D011817:Rabbits
D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D001127:Arginine Vasopressin; D016718:Arachidonic Acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D003577:Cytochrome P-450 Enzyme System; D004072:Digitonin