FIGURE 9.

BI-1 sensitizes cells to cell death induced by acidic conditions. A, cells were cultured in 140 mm K⁺-adjusted medium buffered to the indicated pH in the presence of 5 μm nigericin, and cell viability was measured 48 h later using the trypan blue method. B, mitochondria-enriched heavy membranes and cytosol fractions were obtained from cells at 48 h following treatment in the same medium as in A. The fractions were analyzed by SDS-PAGE/immunoblotting using antibodies recognizing Bax, cytochrome c, Hsp60 (mitochondrial marker), and tubulin (cytosolic marker). Data from blots of three replicate immunoblotting experiments were quantified by scanning densitometry, were normalized relative to Hsp60 for membrane fractions and tubulin for cytosol fractions, and are presented as bar graphs below the immunoblots. Cyt c, cytochrome c.