Epinephrine synthesis in the rat iris.
Epinephrine (E) alters blood flow, intraocular pressure and pupillary constriction. The rat iris contained E-forming activity that was moderately specific for a phenylethanolamine and was inhibited by the phenylethanolamine-N-methyltransferase (PNMT) inhibitor SKF 29661. Unilateral superior cervical ganglionectomy decreased iris norepinephrine (NE) 63%, but failed to lower PNMT activity or E in the iris. Removal of both adrenal medullae markedly lowered circulating E levels, but had no effect on iris E. Further treatment with 6-hydroxydopamine and reserpine greatly lowered iris NE levels, but failed to decrease either iris E or E forming activity. The rat iris has non-neuronal E-forming enzymes which appear to synthesize most of the E contained in the iris.
Elayan
H
H
Department of Medicine, University of California, San Diego Medical Center 92103.
Kennedy
B
B
Ziegler
M G
MG
D000311:Adrenal Glands / Q000201:enzymology; D000818:Animals; D001933:Brain Stem / Q000201:enzymology; D004298:Dopamine / Q000378:metabolism; D004837:Epinephrine / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D015171:Ganglionectomy; D007498:Iris / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D010625:Phenylethanolamine N-Methyltransferase / Q000037:antagonists & inhibitors; D051381:Rats; D011919:Rats, Inbred Strains
D007546:Isoquinolines; C018428:1,2,3,4-tetrahydroisoquinoline-7-sulfonamide; D010625:Phenylethanolamine N-Methyltransferase; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine