Preservation of intermediary metabolism in saponin-permeabilized rat adipocytes

A unique permeabilized adipocyte model is described in which vigorous intracellular intermediary metabolism is preserved through both the pentose and glycolytic-Krebs pathways following saponin-induced pore formation in plasma membranes. Upon addition of appropriate cofactors, the cells metabolize both glucose and glucose 6-phosphate at rates which are severalfold greater than control (membrane-intact) cells. Saponin is shown to mediate these metabolic effects solely by creating membrane pores through which substrate influx occurs. This cell model provides an unprecedented opportunity to examine intermediary metabolism in situ because it permits the entry into the cytosol of previously restricted substrates, modifiers, and radiolabeled compounds. By circumventing the glucose transporter while, for the most part, preserving plasma membrane integrity, these metabolically active, porous adipocytes may permit the direct exploration of postinsulin receptor glucose metabolism by various hormones or drugs.