INHIBITION OF POLYOL FORMATION IN RAT LENS BY VERAPAMIL

Accumulation of sorbitol and xylitol in rat lenses incubated in medium -199 with and without verapamil has been studied. This antihypertensiv e drug, known to attenuate hypertension by its calcium channel blockin g effect, is also known to inhibit cataract formation in diabetes. The present studies have demonstrated that verapamil's effect against cat aract could also be partially related to its aldose reductase inhibito ry activity, in addition to the Ca++ channel blocking activity. The ac cumulation of sorbitol in the lenses incubated with high glucose in th e presence of 400 mu M verapamil was only 2.3 mmoles/Kg wet weight aga inst 11.3 mmoles/Kg in its absence. The level of xylitol attained in t he presence of 10 mM xylose was 25.7 +/- 2.4 mmoles/Kg. It decreased t o 4.8 +/- 1.2 mmoles/Kg in presence of 400 mu M verapamil. Hence, vera pamil is significantly effective in inhibiting lens aldose reductase d ependent polyol synthesis, an action simultaneous with its effect on c alcium penetration.