Effect of pretreatment of germanium-132 on Na(+)-K(+)-ATPase and galactose cataracts.
OBJECTIVE
Recently, we reported that topical administration of 2-carboxyethyl germanium sesquioxide (Ge-132) concurrently with 50% galactose feeding delayed the establishment of mature cataracts and reduced advance glycation product. This study was to determine the effect of pretreatment of Ge-132 on galactose associated morphological changes and Na(+)-K(+)-ATPase activity.


METHODS
Young Sprague Dawley rats received topical eye drops four times a day of either saline or Ge-132 seven days prior to the 50% galactose diet and during galactose feeding. At desired intervals the lenses were extracted, photographed and processed for either light microscopy, scanning electron microscopy or the determination of Na(+)-K(+)-ATPase activity.


RESULTS
In Ge-132 pretreated lenses as compared to saline pretreated lenses the following results were observed: (a) the galactose-induced morphological alterations in the majority of lenses were delayed and (b) Na(+)-K(+)-ATPase activity was protected.


CONCLUSIONS
Our previous and current studies show that in addition to osmotic stress post-translational protein modification, such as glycation, including enzymes may play a role in initiating changes that lead to cataract development. The inhibition of protein glycation by antiglycating compounds, such as Ge-132, delays sugar cataract formation. Currently, we are investigating the status of protein glycation and advanced glycation end products following pretreatment with Ge-132 and the role of Ge-132 on the activities of enzymes such as aldose reductase and Na(+)-K(+)-ATPase.
Unakar
N J
NJ
Department of Biological Sciences, Oakland University, Rochester, MI, USA.
Tsui
J
J
Johnson
M
M
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002386:Cataract / Q000139:chemically induced / Q000201:enzymology* / Q000517:prevention & control; D005690:Galactose; D005857:Germanium / Q000008:administration & dosage / Q000494:pharmacology*; D006031:Glycosylation; D007908:Lens, Crystalline / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D009883:Ophthalmic Solutions; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D011422:Propionates; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000970:Antineoplastic Agents; D009883:Ophthalmic Solutions; D009942:Organometallic Compounds; D011422:Propionates; D005857:Germanium; C066750:propagermanium; D000254:Sodium-Potassium-Exchanging ATPase; D005690:Galactose