Force-velocity and series elastic characteristics of smooth muscle from the hog carotid artery.

The force-velocity and series elastic characteristics of vascular strips from the media of hog carotid arteries were determined using the method of quick release to a known afterload. Shortening velocity was a function of load, and the data could be fitted by a rectangular hyperbola using the Hill equation, (P + a) V = b (Po P), where P is the load, Pois the maximum isometric force developed at the optimum muscle length (Lj, V is velocity, and a and b are constants. The following dynamic constants were obtained for the electrically stimulated strips: estimated maximum shortening velocity for the unloaded muscle (VmJ = 0.12 LJsec, b = 0.02 Wsec, Po = 1.80 kg-wt/cm 2 = 1.76 X 10 dynes/cm, and a/Po = 0.18. Maximum power output occurred at a load of 0.28 Po. The stress-strain curve for the series elastic component could be approximated by the simple exponential equation, stress = 0.034e . The extension of the series elastic component at Po was 7.2% of Lo.