Association of selenium with tissue membranes of ovine and rat tissues.

Rats and lambs were injected with(75)Se-selenite and the microsomal fraction obtained by differential centrifugation from homogenates of muscle, heart, liver, brain, kidney, and testes. These fractions were subsequently centrifuged on sucrose density gradients from 25 to 45% and the distribution of selenium-75 between the labeled membranes of different densities monitored by scintillation counting. The majority of the selenium-75 was associated with membranes of similar density in muscle, heart, liver, and testes from both rats and lambs. The selenium-75 was distributed between many different density membranes in brain from both lambs and rats. The selenium-75 was associated predominantly with one density membrane from ovine kidney but with several density membranes from rat kidney.