title: Spontaneous calcium-independent nitric oxide synthase activity in porcine ciliary processes.
abstract: In the cornea, iris, retina, and ciliary processes of porcine eyes the nitric oxide synthase (NOS) activity was assayed by measuring the transformation of L-[U-14C]-arginine into L-[U-14C]-citrulline: (1) in the absence or presence of the calcium-chelator, ethylene glycol tetra acetic acid (EGTA), and (2) in the presence of EGTA and the false precursor of L-arginine, NG-nitro-L-arginine methyl ester (L-NAME). In the retina and the iris a high calcium-dependent NOS activity was present, while in the cornea the activity was relatively low. In these three tissues no significant calcium-independent NOS activity was detected. In contrast, a marked calcium-independent NOS activity, but no calcium-dependent NOS activity, was found in the ciliary processes. The presence of a spontaneous calcium-independent NOS activity in the ciliary processes suggests that nitric oxide (NO) production is highly regulated in this tissue.
authors.affiliation: Laboratory of Ocular Pharmacology and Physiology, University Eye Clinic Basel, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Haufschild
authors.forename: E
authors.initials: E
authors.lastname: Nava
authors.forename: P
authors.initials: P
authors.lastname: Meyer
authors.forename: J
authors.initials: J
authors.lastname: Flammer
authors.forename: T F
authors.initials: TF
authors.lastname: Lüscher
authors.forename: I O
authors.initials: IO
authors.lastname: Haefliger
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002924:Ciliary Body / Q000201:enzymology*; D003315:Cornea / Q000201:enzymology*; D007498:Iris / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D012160:Retina / Q000201:enzymology*; D013552:Swine
chemical_list: D019001:Nitric Oxide Synthase; D002118:Calcium