Biomaterial Database

Kinetics of rhodopsin bleaching in the isolated human retina. 1973

C Baumann, and S Bender

1. Pieces of human retina were dissected from eyes enucleated because of malignant tumours. The isolated retinas were perfused by an ionic medium (36 degrees C) and investigated spectrophotometrically.2. Rhodopsin was identified on the basis of its difference spectrum. The maximum absorbance change on bleaching was about 0.1 (lambda = 500 nm).3. The process of bleaching was quantitatively analysed in terms of four slow reactions, viz. (a) conversion of metarhodopsin II into metarhodopsin III, (b) hydrolysis of metarhodopsin II into retinal and opsin, (c) decay of metarhodopsin III to retinal, and (d) reduction of retinal to retinol.4. First-order rate constants for the reactions in 3 were 9 x 10(-3) sec(-1) (a), 3 x 10(-3) sec(-1) (b), 4 x 10(-3) sec(-1) (c), and 3 x 10(-2) sec(-1) (d).5. With two simplified versions of the model summarized in 3 and 4, the description of experimental data was less accurate.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010775	Photic Stimulation	Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.	Stimulation, Photic,Visual Stimulation,Photic Stimulations,Stimulation, Visual,Stimulations, Photic,Stimulations, Visual,Visual Stimulations
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D003623	Dark Adaptation	Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.	Scotopic Adaptation,Adaptation, Dark,Adaptation, Scotopic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012168	Retinal Pigments	Photosensitive protein complexes of varied light absorption properties which are expressed in the PHOTORECEPTOR CELLS. They are OPSINS conjugated with VITAMIN A-based chromophores. Chromophores capture photons of light, leading to the activation of opsins and a biochemical cascade that ultimately excites the photoreceptor cells.	Retinal Photoreceptor Pigment,Retinal Pigment,Visual Pigment,Visual Pigments,Retinal Photoreceptor Pigments,Photoreceptor Pigment, Retinal,Photoreceptor Pigments, Retinal,Pigment, Retinal,Pigment, Retinal Photoreceptor,Pigment, Visual,Pigments, Retinal,Pigments, Retinal Photoreceptor,Pigments, Visual
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In