Vasoconstriction in isolated goat aorta does not increase mean aortic pressure

Vasoconstriction in small arteries and arterioles is known to increase resistance to flow, while vasoconstriction in large arteries and aorta is known to decrease their compliance. Besides this general understanding, there is no systematic documentation on what happens to small artery compliance and large artery resistance during vasoconstriction and the corresponding alterations in vascular pressure. The aim of the study is to assess the effect of adrenaline on goat aortae and small arteries in terms of resistance and compliance. Isolated goat aortae and small arteries were perfused with a pulsatile pump and lumen pressure was recorded before and after addition of adrenaline. In the aortae, systolic pressure increased, diastolic pressure decreased, pulse pressure increased (p = 0.018, WSR); but the mean pressure remained the same (p = 0.357, WSR). Small artery vasoconstriction caused an increase in systolic, diastolic and mean pressures (p = 0.028, WSR). Using length, radius, and thickness data from the tissues and the tubes of the experimental set-up, electrical models were simulated to understand the biological data. The simulations allow us to infer that vasoconstriction in aorta leads to a reduction in compliance, but an increase in resistance if any, is not sufficient to change the mean aortic pressure. On the other hand, vasoconstriction in small arteries increases resistance, but a decrease in compliance if any, does not affect any of the four pressure parameters measured. Vasoconstriction in aorta decreases compliance and therefore increases pulse pressure but does not change resistance significantly enough to alter mean pressure. Key Points Summary ### Competing Interest Statement The authors have declared no competing interest.