Fig. 4. Histamine release, if vancomycin (n = 8), calcium ionophore A23187 (n = 11), morphine (n = 11), or atracurium (n = 9) is added to human cutaneous mast cells without calcium and magnesium in the buffer. The histamine release is calculated as (drug released histamine)/(total histamine content) × 100%. The baseline for each group of drugs is presented together with the drug release. *Significant difference from baseline release (P < 0.05).