Content and binding of aldosterone in human ocular lens

The concentration of aldosterone was determined by radioimmunoassay in homogenates from a total of 227 human cataractous lenses divided into six groups according to age and accompanying diseases (i.e. glaucoma, essential hypertension, diabetes and combination of the two latter diseases). Aldosterone concentration in cataracts ranged from 0.020 to 0.036 fmol mg-1 protein. Significantly higher values were found in lenses of patients with hypertension (0.047 +/- 0.022 fmol mg-1 protein). Using two independent methods an evidence was brought that specific and saturable aldosterone binding occurs in cytosol of human lens epithelium obtained from autopsy specimens, which is not identical with glucocorticoid binding. Electrophoretic properties of this aldosterone binding entity correspond to a protein with a relative molecular mass of 90 000 daltons.