Allantoin induces calcium influx in CHO -cells transfected with imidazoline receptors. The expression of DDK (A) or NISCH (B) was identified using Western blotting analysis. Changes in intracellular calcium by agmatine (open bar) or allantoin (gray bar) were detected using the fura-2 probe by a fluorescence spectrofluorometer (C). All of the values are expressed as the mean ± SEM (n = 6 per group). *P < 0.05, **P < 0.01 and ***P < 0.001 compared with the control group.