Mark Albrecht; Brock Orme; Mary Jo Tufte, Southern Utah University
Plants produce a series of compounds known as secondary metabolites which are not essential for primary growth or development, but do provide advantages such as chemical protection from herbivores or coloration to attract pollinators. Terpenoids are the largest category of plant-produced secondary metabolites. Terpenoids have been found to cause vasodilation in rat aortae and mesenteric arteries. However, previous research has shown that vasoconstriction occurs when the essential oil from Umbellularia californica is applied to small cutaneous blood vessels in leopard frogs (Rana pipiens). This essential oil is composed of several terpenoids, including terpinen-4-ol. To explore the possible cause of the observed vasoconstriction, we focused on this terpenoid in an isolated study. We applied the compound directly to cutaneous microvasculature in resected portions of frog skin and recorded changes in blood vessel diameter. Terpinen-4-ol caused a sustained reversible vasoconstriction of blood vessels in a concentration dependent manner. Our results suggest that Terpinen-4-ol may be partially responsible for the observed vasoconstriction caused by U. californica essential oil.