Effects of intracellular calcium on lens membrane permeability
作者:
HightowerK. R.,
HarrisonS. E.,
UnakarN. J.,
TsuiJ.,
期刊:
Current Eye Research
(Taylor Available online 1985)
卷期:
Volume 4,
issue 6
页码: 693-701
ISSN:0271-3683
年代: 1985
DOI:10.3109/02713688509017664
出版商: Taylor&Francis
数据来源: Taylor
摘要:
The present investigation was designed to assess whether lens membrane permeability is affected by changes in levels of intracellular calcium. Lanthanum, an inhibitor of Ca-ATPase, affected an increase in the concentration of intracellular calcium (Ca1) measured in cortical fiber cells. Preculture of lenses in lanthanum (1.0mM) caused an accumulation of36Cl during subsequent culture at a rate three-fold higher than control lenses. Changes in calcium levels, however, were not responsible for the observed flux changes because a 40mV depolarization was observed to occur prior to a significant increase in calcium levels. The non-specific effects of lanthanum and other potential inhibitors of calcium transport were avoided by preculturing lenses in an ion-HEPES medium containing 20mM calcium chloride. In lenses with a six-fold increase in calcium levels there resulted only a 10% increase in36Cl uptake over a 3 hr period.86Rb efflux was also measured and the rate constant was unchanged compared to control lenses. Calcium accumulation did lead to a small (8mV) depolarization which may account for the small increase in chloride accumulation. By light microscopy, morphology of cortical lens fibers and the epithelium appeared unchanged in the calcium-loaded lens. The results provide little evidence that an increase in Ca1leads to acute changes in lens membrane permeability.
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