A method is described whereby short fragments of rat kidney tubule were obtained when kidney slices were gently dispersed by exposure to collagenase and hyaluronidase. When suspended in buffered saline the fragmented tubules respired actively over a period of several hours, the rate of oxygen consumption being proportional to the amount of cell protein. Oxygen uptake was stimulated by the addition of glucose, lactate, butyrate, α-oxoglutarate and other substrates and was decreased by the omission of Ca2+ from the suspending medium. With α-oxoglutarate as the added substrate, dinitrophenol strongly stimulated oxygen uptake. Dinitrophenol had a less-marked stimulatory effect when glucose was the added substrate, and inhibited respiration in the absence of added substrate. Oligomycin inhibited respiration and this inhibition was partially reversed by dinitrophenol. Fragmented tubules synthesized glucose from lactate at a high rate but this capacity for gluconeogenesis was abolished by dinitrophenol and by physically damaging the cells.
