Determination of Histamine Levels in the Yellow Stingray, Urobatis jamaicensis

Determination of Histamine Levels in the Yellow Stingray, Urobatis jamaicensis

Alvin Sherman Library 1054

Histamine, 5-imidazole-ethylamine (MW = 111), is an important mediator of the immune system and is most often found in the initial phase of an anaphylactic reaction. In previous studies histamine molecules have been found to be synthesized and released by mast cells and the basophilic leukocytes upon an exposure to allergens. In mammals, the primary physiological effects of peripheral histamine include bronchoconstriction and vasoconstriction. Although much work has been done examining histamine levels in higher vertebrates and teleost fishes, to date, we found no published research on histamine levels in elasmobranchs. We examined circulating histamine levels in elasmobranch blood, specifically in the yellow stingray, Urobatis jamaicensis. Enzyme Linked Immunoabsorbant Assay (ELISA) was used to determine the levels of histamine in whole blood, blood plasma, and white blood cells of three stingrays. White blood cells were isolated from red cells and plasma by differential centrifugation. Results indicated the presence of histamine in the whole blood, plasma, and white blood cells. However, the dramatically higher levels of histamine in the white blood cell fraction over the other blood fractions supports the hypothesis that like other vertebrates, histamine in elasmobranchs originates in white blood cells.