Increased dietary NaCl intake influences lens transport properties in Sprague-Dawley rats.

Abstract

Several years ago, we reported a high frequency of cataracts in Dahl salt-sensitive rats (DS) which led us to carry out a series of studies, such as longitudinal ouabain-sensitive lens 86Rb uptake measurements. Yet, throughout all of our work, we used the Dahl salt-resistant rat (DR) as our control group, despite the fact that DR is a strain resistant to even experimental hypertension such as that resulting from renal cellophane wrapping. Thus, in the present study we assessed lens short-circuit current (Isc) in adult Sprague-Dawley rats (SD) from which DS and DR were derived. Sprague-Dawley rats were studied during chronic normal vs high NaCl intake. These studies showed that basal Isc and calculated translenticular potential difference (PDt) were nearly doubled by this dietary regimen. Sequential addition of BaCl2 and ouabain to the isolated lens anterior surface bath also revealed increased BaCl2-sensitive as well as BaCl2- and ouabain-insensitive lens Isc in SD kept on a high NaCl diet. There was a statistically insignificant tendency for lens ouabain-sensitive Isc to increase in SD given a high NaCl diet. These findings were unrelated to levels of arterial blood pressure which were not altered by chronic high NaCl intake in adult SD. Our data suggest the possibility of increased lens barium and ouabain insensitive ionic permeabilities combined with possibly increased lens fiber potassium concentration, as a response to chronic high dietary NaCl in the normal rat. The nature of the barium and ouabain insensitive component of the lens Isc that rises during chronic high NaCl intake requires elucidation.(ABSTRACT TRUNCATED AT 250 WORDS)