Zinc uptake in vitro by human retinal pigment epithelium
Zinc, an essential trace element, is present in unusually high concentrations in the chorioretinal complex relative to most other tissues. Because little has been known about the interactions between the retinal pigment epithelium and free or protein-associated zinc, we studied /sup 65/Zn uptake by human retinal pigment epithelium in vitro. When monolayers were exposed to differing concentrations from 0 to 30 microM /sup 65/Zn in Dulbecco's modified Eagle's medium with 5.4 gm/l glucose at 37 degrees C and 4 degrees C, we observed a temperature-dependent saturable accumulation of the radiolabel. With 15 microM /sup 65/Zn, we saw a biphasic pattern of uptake with a rapid first phase and a slower second phase over 120 min. Uptake of /sup 65/Zn was inhibited by iodacetate and cold, and reduced approximately 50% by the addition of 2% albumin to the labelling medium. Neither ouabain nor 2-deoxyglucose inhibited uptake. Cells previously exposed to /sup 65/Zn retained approximately 70% of accumulated /sup 65/Zn 60 min after being changed to radiolabel-free medium. Following removal of cells from the extracellular matrix adherent to the dish bottom, a variable amount of nonspecific binding of /sup 65/Zn to the residual matrix was demonstrated. These observations are consistent with a facilitated type of transport and demonstrate the ability of human retinal pigment epithelium in vitro to accumulate and retain zinc.
- Research Organization:
- Louisiana State Univ. Medical Center School of Medicine, New Orleans
- OSTI ID:
- 5664118
- Journal Information:
- Invest. Ophthalmol. Visual Sci.; (United States), Vol. 28:11
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ZINC
BIOLOGICAL ACCUMULATION
UPTAKE
CONJUNCTIVA
EPITHELIUM
FIBROBLASTS
IN VITRO
MAN
MEMBRANE TRANSPORT
RETINA
TEMPERATURE DEPENDENCE
TRACER TECHNIQUES
ZINC 65
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
BODY AREAS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
EYES
FACE
HEAD
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANES
METALS
MUCOUS MEMBRANES
NUCLEI
ORGANS
PRIMATES
RADIOISOTOPES
SENSE ORGANS
SOMATIC CELLS
TISSUES
VERTEBRATES
ZINC ISOTOPES
560300* - Chemicals Metabolism & Toxicology
550501 - Metabolism- Tracer Techniques