Lenticular alterations in hypertensive rats

Cataract development has been reported in Dahl salt-sensitive (DS) hypertensive rats with high-salt intake. An alteration in ionic transport and electrolyte balance has been reported to be associated with hypertension in these animals. A morphological evaluation of the lenses of salt-sensitive 'cataract-prone' (DS) and salt-resistant (DR) control animals is lacking. We undertook this investigation to evaluate changes in lenticular morphology and in systolic blood pressure (SBP) following administration of high-salt. Both DS and DR rats were given high-salt for up to 33 weeks. Lenses were extracted at desired intervals following the initiation of the high-salt diet and processed for light and transmission electron microscopy. Except for some variations between animals, our study showed that DR rats, in general, exhibited normal SBP and relatively normal morphology. In comparison, the lenses of DS hypertensive rats demonstrated the following major changes: (1) some epithelial cells showed multilayering, nodule formation, pyknotic nuclei, swelling of cell organelles, presence of a large number of lysosomes, and distension of intercellular spaces, (2) disorganization of the bow and (3) swelling of fiber cells in the equatorial region. These changes were similar to those observed in precataractous stages during the development of several types of experimentally induced cataracts and indicate an alteration in normal electrolyte balance as well as hyperosmolarity. Changes in ion transport and electrolyte imbalance have been reported in the lenses of DS rats on high-salt diet. These alterations and a defect in the sodium-potassium pump may be responsible for cataract development in these hypertensive rats.