LENTICULAR ALTERATIONS IN HYPERTENSIVE RATS

Cataract development has been reported in Dahl salt-sensitive (DS) hyp ertensive rats with high-salt intake. An alteration in ionic transport and electrolyte balance has been reported to be associated with hyper tension in these animals. A morphological evaluation of the lenses of salt-sensitive 'cataract-prone' (DS) and salt-resistant (DR) control a nimals is lacking. We undertook this investigation to evaluate changes in lenticular morphology and in systolic blood pressure (SEP) followi ng administration of high-salt. Both DS and DR rats were given high-sa lt for up to 33 weeks. Lenses were extracted at desired intervals foll owing 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 S EP and relatively normal morphology. In comparison, the lenses of DS h ypertensive rats demonstrated the following major changes: (1) some ep ithelial 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 b ow and (3) swelling of fiber cells in the equatorial region. These cha nges were similar to those observed in precataractous stages during th e development of several types of experimentally induced cataracts and indicate an alteration in normal electrolyte balance as well as hyper osmolarity. Changes in ion transport and electrolyte imbalance have be en reported in the lenses of DS rats on high-salt diet. These alterati ons and a defect in the sodium-potassium pump may be responsible for c ataract development in these hypertensive rats.