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The speed with which horseflies (Diptera: Tabanidae) obtain a bloodmeal suggests they have potent vasodilators. We used isolated perfused rat heart to examine the vasoactivity of salivary gland extracts (SGEs) of three horsefly species, Hybomitra bimaculata Macquart, Tabanus bromius Linnaeus and Tabanus glaucopis Meigen. Administration of horsefly SGEs to the heart produced biphasic coronary responses: a decrease and subsequent increase in coronary flow (CF), characterized by initial vasoconstriction followed by prolonged vasodilation of coronary vessels. However, although SGEs of H. bimaculata induced a significant decrease in left ventricular pressure (LVP), the effect on changes in CF was not significant except at the highest dose tested. The ability to reduce LVP without significantly lowering CF, or affecting heart rate and rhythm, represents a unique set of properties that have considerable therapeutic potential if they can be reproduced by a single molecule.

Original publication




Journal article


Med Vet Entomol

Publication Date





384 - 389


Animals, Coronary Circulation, Coronary Vessels, Diptera, Dose-Response Relationship, Drug, Feeding Behavior, Heart Rate, Male, Rats, Rats, Wistar, Salivary Glands, Species Specificity, Tissue Extracts, Vasodilation, Vasodilator Agents, Ventricular Pressure