Instantaneous and continuous measurement of 14C-labeled substrate oxidation to 14CO2 by minute tissue specimens: an ionization chamber method.

The vibrating reed electrometer and ionization chamber have been adapted for the instantaneous and continuous measurement of 14C-labeled substrate oxidation to 14CO2 by minute quantities of isolated tissues. This modified technique, utilizing a "closed" circulation incubation system, is 10-50 times as sensitive as the previously described "open" circulation techniques. Substrate oxidation curves are described for human erythrocytes and polymorphonuclear leucocytes, canine parietal cells and isolated segments of the rat nephron. This apparatus should prove to be a useful tool for metabolic studies of small quantities of isolated tissue.