Correlation between Amplitude and Frequency of Spontaneous Rhythmic Contractions and the Mean Circumferential Wall Stress of a Small Muscular Artery

The ability of isolated small peripheral vessels to develop spontaneous rhythmic contractions has been well known for more than 40 years (for review see (4)). Most experimental work on this topic has been done on helical strips of arteries or on longitudinal strips of veins. Without any doubt such simple muscle preparations, in which the basic geometrical state of the vessel is altered, may be helpful as an analytical framework for the traditional approach in smooth muscle mechanics, i.e. the description of general relationships between force, length, time, and velocity of the muscle. It must be emphasized, however, that results obtained on vessel strips can be transferred to a vessel with an intact cylindrical wall structure only with considerable reservations. This applies not only to studies on the passive mechanical wall behaviour, but also to studies on the spontaneous mechanical activity. Depending on the direction of cutting, the propagation from cell to cell via low-resistance gap junctions is confined. An optimal synchronization, which in the end determines the strength as well as the overall frequency of the spontaneous contractions, can only be reached in an intact vessel.