Figure 6. IF1 and low extracellular P_i inhibit extracellular ATP synthesis in αT3–1 cells.

Studies sought to regulate F₀F₁ ATP synthase activity at the cell surface in αT3–1 cells. In A, αT3–1 cells were treated with increasing doses of IF1 (0.1 and 1.0 μg/mL) and vehicle (open bars) or ADP (10μM; black bars) for a 1-hour period. Extracellular ATP levels were then assayed. IF1 blunted (P < .05) extracellular ATP synthesis in a dose-dependent manner. In B, similar studies were carried out examining the effects of reduced P_i in the absence or presence of ADP in the culture media. Media deficient in P_i could not support (P < .05) extracellular ATP synthesis in αT3–1 cells compared with media replete with P_i. Differing letters depicted over bars within a study designate statistical significance (P < .05).