Transport of 3-O-methylglucose in isolated rat retinal pigment epithelial cells.
The uptake of 3-O-methylglucose in isolated rat retinal pigment epithelial cells exhibits complex kinetics as revealed by a plot of the Lineweaver-Burke transformation of the Michaelis-Menten equation. Conventional analysis of the linear portion of the double-reciprocal plot yields a Km of 7 . 69 mM and a Vmax of 1 . 95 nM/mg protein/min. If data are analyzed to take into account the existence of two carrier-mediated processes, a high affinity system (Km = 1 . 94 mM, Vmax = 0 . 012 nM/mg protein/min) and a low affinity system (Km = 640 mM, Vmax = 12 . 20 nM/mg protein/min) for 3-O-methylglucose uptake results. Three-O-methylglucose accumulation over a 10-min period was insensitive to phloridzin (0 . 1 mM), ouabain (1 mM) and dinitrophenol (1 mM), but was inhibited by mercuric chloride (1 mM). Phloretin (0 . 1 mM) increased the accumulation of both glucose and 3-O-methylglucose, which may indicate the existence of carrier-mediated efflux system. These findings demonstrate that glucose transport in rat retinal pigment epithelial cells is a complex process involving carrier mediation.
D019325:3-O-Methylglucose; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004136:Dinitrobenzenes / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D010693:Phloretin / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D051381:Rats
D004136:Dinitrobenzenes; D008757:Methylglucosides; D008759:Methylglycosides; D019325:3-O-Methylglucose; D010042:Ouabain; D005947:Glucose; D010693:Phloretin