Fig. 1
Influence of hydrochloric- and lactic acidosis on pHi and cellular viability. A pHi was determined by BCECF measurements. The BCECF fluorescence ratio was calibrated by using two nigericin solutions of known H+ concentration. Short-term (10 min) (B; N = 4; n = 42–93; *p ≤ 0.0001 vs. ctrl.) and chronic extracellular acidification (48 h) (C; N = 3; n = 35–42; *p ≤ 0.0001 vs. ctrl.) led to rapid and sustained intracellular acidification to a similar extent. Cellular viability was determined by protein content (D), LDH release (E), and caspase activity (F) for 48 h. Both types of acidosis did not decrease cellular protein content (N = 4–7, n = 15–21), nor induce necrotic (N = 4–8, n = 15–24) or apoptotic cell death (N = 3–7, n = 12–21); *p ≤ 0.01 vs. ctrl