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A salivary vasodilator in the blood‐sucking bug, Rhodnius prolixus
Author(s) -
Ribeiro José M.C.,
Marinotti Osvaldo,
Gonzales Rafael
Publication year - 1990
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1990.tb14183.x
Subject(s) - rhodnius prolixus , histamine , chemistry , salivary gland , saliva , endocrinology , medicine , vasodilation , acetylcholine , pharmacology , biochemistry , biology , ecology , insect
1 Salivary gland homogenates of the blood‐sucking bug, Rhodnius prolixus induced transient, dose‐dependent relaxation of rabbit aortic preparations pre‐constricted with 200 ng ml −1 noradrenaline, 1 μg ml −1 histamine or 20 ng ml −1 angiotensin II. Such relaxations were less marked when the aorta was constricted by 60 m m KCl. These effects were observed with as little as 0.2 μg ml −1 of crude salivary gland protein. 2 The vasodilator effect was endothelium‐independent, abolished by 50 μ m hydroquinone or 50 μ m methylene blue, and potentiated by 30 u ml −1 superoxide dismutase. 3 Salivary homogenates generated a coloured compound when reacted with sulfanilic acid in the presence of N‐(1‐naphtyl)‐ethylediamine, indicating the presence of reactive nitrogen groups, equivalent to 35 ± 3 ng of sodium nitrite per pair of glands. 4 Molecular sieving high performance liquid chromatography of salivary gland homogenates generated a single peak of vasorelaxant activity which coincided with the presence of platelet antiaggregating and spasmolytic (guinea‐pig ileum contracted with histamine) activities, as well as with reactive nitrogen groups. 5 It is concluded that a protein of molecular weight 16,500 daltons in the salivary glands of R. prolixus contains reactive nitrogen groups which assist the bug during a blood meal. It is suggested that saliva of blood sucking arthropods is a natural resource of novel pharmacological activities.