Micromethods for the simultaneous measurement of intracellular potassium and corticosterone output of isolated adrenal cortical cells.

1. A technique is described for the measurement of potassium and water spaces in less than 1 mul of packed cells. 2. The total potassium content of cell pellets is measured in a perchloric and nitric acid extract by flame spectrophotometry. The potassium in trapped medium is estimated from the distribution space of hydroxy[-14C]methylinulin and subtracted from the total potassium content to give intracellular potassium content. Corticosterone output was measured by radioimmunoassay. 3. The simultaneous measurement of total water from the [-3H]water space allows calculation of the intracellular water space. 4. Values obtained for intracellular potassium content, intracellular water space and calculated intracellular potassium concentration are presented for different preparations of isolated adrenal cortical cells.