Altered lens short-circuit current in adult cataract-prone Dahl hypertensive rats

Carmen Rodríguez-Sargent, Estela S. Estapé, Nadia Fernández, Jaime E. Irizarry, José L. Cangiano, Oscar A. Candia

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We assessed components of lenticular short-circuit current in adult hypertensive Dahl salt-sensitive rats (DS) during chronic control (0.4% sodium) versus high (3% sodium) dietary NaCl intake begun at the age of 4 weeks until rats were studied. We also evaluated the influence of barium, a potassium channel blocker, and ouabain, a specific inhibitor of Na+,K+- ATPase activity, by adding them into the anterior lens surface, thus measuring barium-sensitive ouabain-sensitive, and barium- and ouabain- insensitive short circuit currents. During control NaCl intake, short- circuit current in DS and their control group, Dahl salt-resistant rats (DR), did not differ significantly. DS were subclassified into cataract-prone rats and rats unlikely to develop cataracts on the basis of their pressor response to the change from a normal to high NaCl diet during the first weeks of age. Although only transparent lenses were studied, total lens short-circuit current was already markedly decreased in the cataract-prone subgroup compared with DS unlikely to develop cataracts and control DR. This was in sharp contrast to the increase in short-circuit current previously reported in Sprague-Dawley rats and now observed in control DR in response to high dietary NaCl. The decrease in lens short-circuit current in cataract-prone rats was associated with lower absolute values of barium- and ouabain- sensitive short-circuit currents as well as with low barium- and ouabain- insensitive short-circuit current. Although the barium- and ouabain-sensitive components of the short-circuit current were similar in DS unlikely to develop cataracts and DR, the barium- and ouabain-insensitive components of the short-circuit current was lower in DS unlikely to develop cataracts than values in DR. Interestingly, this component of lens short-circuit current also increased in DR during chronic high NaCl, whereas the opposite change occurred in cataract-prone DS and DS unlikely to develop cataracts. Thus, the barium- and ouabain-insensitive short-circuit current may be a mechanism that protects the normal lens from developing cataracts. Possible candidates for this short-circuit current component are voltage-dependent potassium channels, calcium-activated potassium channels, or both. Our studies show altered lens short-circuit current in response to high NaCl intake in cataract-prone DS and suggest the possibility of altered lens potassium transport during submitted hypertension but before loss of lens transparency.

Original languageEnglish
Pages (from-to)440-443
Number of pages4
JournalHypertension
Volume28
Issue number3
DOIs
StatePublished - Sep 1996

Keywords

  • cataract
  • lens, crystalline
  • potassium channels
  • sodium chloride, dietary

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