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

Abstract

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(P(0) - P), where P is the load, P(o) is the maximum isometric force developed at the optimum muscle length (L(0)), 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 (Vmax) = 0.12 L(0)/sec, b = 0.02 L(0)/sec, P(0) = 1.80 kg wt/cm2 = 1.76 x 10' dynes/cm2, and a/P(o) 0.18. Maximum power output occurred at a load of 0.28 P(o). The stress strain curve for the series elastic component could be approximated by the simple exponential equation, stress 0.034e(0.58 strain). The extension of the series elastic component at P(o) was 7.2% of L(o).