Fig. 1.

ATP receptors are involved in the NAD⁺-induced increase in [Ca²⁺]_i. Monocytes were preincubated with PPADS (30 μM) for 25 min and continuously perfused with PPADS during the addition of NAD⁺ (200 μM, 80 s; a). Intracellular Ca²⁺ levels were measured as the change in the 340 nm/380 nm emission ratio. Values obtained in the presence of NAD⁺ were set as the 100% reference. Results are means ± SEM of six measurements. ***P < 0.001 (Student’s t test). Monocytes were incubated with 200 μM NAD⁺ (black bar) before 100 μM ATP (open bar) was added in a Ca²⁺-containing (solid line) or Ca²⁺-free (dotted line) solution (b). Shown is the 340 nm/380 nm emission ratio from one representative measurement. ***P < 0.001 (Student’s t test) Δ ratio 340/380 NAD⁺ + Ca²⁺ versus NAD⁺ − Ca²⁺ (n = 3)