A salivary vasodilator in the blood-sucking bug, Rhodnius prolixus.
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 microgram ml-1 histamine or 20 ng ml-1 angiotensin II. Such relaxations were less marked when the aorta was constricted by 60 mM KC1. These effects were observed with as little as 0.2 microgram ml-1 of crude salivary gland protein. 2. The vasodilator effect was endothelium-independent, abolished by 50 microM hydroquinone or 50 microM methylene blue, and potentiated by 30 mu ml-1 superoxide dismutase. 3. Salivary homogenates generated a coloured compound when reacted with sulfanilic acid in the presence of N-(1-naphthyl)-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 anthropods is a natural resource of novel pharmacological activities.
Ribeiro
J M
JM
Department of Tropical Public Health, Harvard School of Public Health, Boston, MA 02115.
Marinotti
O
O
Gonzales
R
R
D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007313:Insecta / Q000502:physiology*; D008297:Male; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012463:Saliva / Q000502:physiology*; D013482:Superoxide Dismutase / Q000494:pharmacology; D014020:Tissue Extracts / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
D010975:Platelet Aggregation Inhibitors; D014020:Tissue Extracts; D014665:Vasodilator Agents; D013482:Superoxide Dismutase; D011188:Potassium