Increased intracellular ppGpp levels in Hp cells in the absence of CO
. Hp 26695 was cultured in liquid media for 1 h under an aerobic condition in the absence or presence of 10% CO2, and intracellular nucleotide levels were determined by HPLC analysis. Results are presented as mean ± SD of values obtained from triplicate cultures. Data shown are representative of three independent experiments.