FIGURE 3.

NAADP is synthesized and metabolized by tracheal tissue. A, chemical structures and scheme showing NAADP synthesis via base exchange and metabolism by reported mechanisms. B and C, HPLC traces showing NAADP synthesis by base exchange using tracheal tissue homogenate incubated with NADP (1 mm) and nicotinic acid (NA; 10 mm) at pH 5 (B) and pH 7 (C). D, HPLC traces showing NAADP metabolism. NAADP (100 μm) was incubated with homogenate at pH 7. All reactions contained tracheal homogenate at 5% (w/v) and were incubated at 37 °C. Peaks were identified by the elution times of authentic samples. NiAM, nicotinamide; ADPR-P, ADP-ribose phosphate; NAAD, nicotinic acid adenine dinucleotide; Abs, absorbance.