title: Effects of volatile anesthetics on light-induced proton uptake of rhodopsin in bovine rod outer segment disk membrane.
abstract: The effects of volatile anesthetics upon the function of bovine rhodopsin were estimated from the measurements of light-induced proton uptake. The light-induced pH changes were measured at both 20 degrees C and 37 degrees C with suspensions to which volatile anesthetics were added in the liquid form. Each anesthetic depressed the light-induced proton uptake concentration-dependently. The anesthetic-induced depression was greater at 37 degrees C than at 20 degrees C. For each anesthetic the concentration needed to depress the proton uptake by 10% was roughly identical to that used clinically. Anesthetics also were added to the suspensions in the gaseous form with air. The light-induced proton uptake was decreased in proportion to the partial pressure of the anesthetic. The partial pressures of halothane and methoxyflurane that depressed the proton uptake by 10% at 37 degrees C were 2.0 x 10(-7) and 1.1 x 10(-2) atm., respectively. From these facts it is suggested that volatile anesthetics affect the light-induced conformational changes of rhodopsin molecule during the metarhodopsin I to metarhodopsin II transition and cause inhibition of the light-induced proton uptake of rhodopsin in the rod outer segment disk membrane.
mesh_terms: D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008027:Light; D008563:Membrane Lipids / Q000032:analysis; D010786:Photoreceptor Cells / Q000378:metabolism*; D011487:Protein Conformation / Q000187:drug effects; D011522:Protons; D012168:Retinal Pigments / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D014835:Volatilization
chemical_list: D000777:Anesthetics; D008563:Membrane Lipids; D011522:Protons; D012168:Retinal Pigments; D012243:Rhodopsin