CORTICOSTEROID-POTENTIATED VASCULAR-RESPONSES OF THE EQUINE DIGIT - POSSIBLE PHARMACOLOGIC BASIS FOR LAMINITIS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 40  (1) , 135-138
Abstract
Spirally cut digital arteries and veins were mounted isotonically in organ baths containing oxygenated Krebs'' Q-Henseleit solution. Twelve arterial and 12 venous preparations all contracted dose dependently when epinephrine, norepinephrine, serotonin, or histamine were added to the bathing fluid. Addition of hydrocortisone or betamethasone alone did not cause contractions in any of the tissues testd. When hydrocortisone or betamethasone was added to vessel strips that were partially contracted (40% to 60% maximal) by epinephrine, norepinephrine or serotonin, each vessel strip invariably underwent an additional contraction. In venous and arterial strips, dose-response curves to epinephrine, norepinephrine, serotonin or histamine were established in the absence and in the presence of corticosteroid. Effects of the amines, except histamine, were markedly potentiated. The degree of corticosteroid/amine potentiation was greater for epinephrine than for norepinephrine and greater in the digital vein than in the corresponding artery from the same animal. Betamethasone was more potent than hydrocortisone. Clinical experience with the antiinflammatory corticosteroids has been that, when used by the intraarticular route, these drugs may cause laminitis.