Histamine and serotonin (5-hydroxytryptamine) are two amino acid derivatives with important biological functions [1]. Histamine, an endogenous monoamine, is synthesized from the histidine and is stored in most tissues and degraded in liver by histaminase. The most important roles of histamine are: mediation of type I allergic reactions, stimulation of stomach secretion of hydrochloric acid and pepsin (as autacoid), and functioning as a neurotransmitter (especially in the central nervous system)[2]. Regarding the vascular effects of histamine in non-ocular territories, there have not been many published literature reviews, for example, there are data reviewed for pulmonary artery[3], brain territory[4], but these data are not recent.