Vascular smooth muscle contraction

Vascular smooth muscle refers to the particular type of smooth muscle found within, and composing the majority of the wall of blood vessels. The main function of vascular smooth muscle tonus is to regulate the caliber of the blood vessels in the body. Excessive vasoconstriction leads to high blood pressure, while excessive vasodilation as in shock leads to low blood pressure (http://en.wikipedia.org/wiki/Vascular_smooth_muscle).

血管平滑肌，指存在于血管内壁并构成其大部分结构的特定类型平滑肌。血管平滑肌的张力作用主要在于调节体内血管的直径。血管过度收缩导致高血压，而血管过度舒张，如休克状态，则导致血压降低（http://en.wikipedia.org/wiki/Vascular_smooth_muscle）。