Figure 1

Medium alkalinization of C. roseus suspension cultured cells in response to UV-B irradiation and its inhibition by suramin. (a)Six-day-old cell suspension cultures were either irradiated with UV-B or left untreated for various periods of time and the pH of the medium was measured at the times indicated after the start of irradiation. Alkalinization response (AR or Δ pH) was measured as described in materials and methods. Inset: Early medium alkalinization response to 5 min of UV-B irradiation (b) Inhibition by suramin of UV-B-induced medium alkalinization. Cells were pre-treated with 1 mM suramin or 1 mM heparin for 10 min prior to irradiation with different doses of UV-B, and as control, cells were irradiated with UV-B alone and the pH of the medium was measured after 10 min. The increase in medium pH (Δ pH) is indicated as the difference between the pH at time 0 and at 10 min. Bars represent the means ± SD (n = 6).