Response of arterial smooth muscle to length perturbation

Department of Anatomy and Department of Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3 The ability of arterial smooth muscle to generate tension is influenced by muscle length. An unsettled question is whether the length-tension relationship is a simple reflection of the contractile filament overlap, as it is in skeletal muscle. There are several factors that could potentially affect tension generation in arterial smooth muscle; these include stretch-induced myogenic response and length-oscillation-induced disruption of the contractile filament organization. In this study, in which rabbit carotid arterial preparations were used, we found that different length-tension curves could be obtained at different times after a length change. In addition, length oscillation at a frequency of normal pulse rate and with small to moderate oscillation amplitude was found to potentiate tension generation but reduced tension at large amplitudes. The observed response could be attributed to adaptation of the muscle to length change over time and to myogenic potentiation associated with stretching of the muscle. carotid artery; length oscillation; tension recovery; plasticity