Oocytes of Rana pipiens were incubated in "Na-Ringer's solution and "Nal 3 Na exchange in the nucleus and cytoplasm followed by low-tempeiature microdissection. Cytoplasmic sodium consists of 2 kinetic fractions: the larger (88 %) slowly exchanging (t^ ~ 2 days), and the smaller (12%) rapidly exchanging (ij ~ 53 min). Nuclear sodium consists of a single fraction whose concentration is similar a...

Hydrogen peroxide inhibition of maximum Ca2+-ATPase and Na+,K+-ATPase activity was measured in a membrane-enriched preparation of rabbit lens cortical fibers and epithelium. At 5 X 10(-6) M hydrogen peroxide maximum Ca2+-ATPase activity was inhibited by 39%, while maximum Na+,K+-ATPase activity was stimulated. Ca2+-ATPase activity was almost completely inhibited at 5 X 10(-4) M hydrogen peroxid...