Arterial wall mechanics and composition and the effects of smooth muscle activation.

A comparison of passive mechanics and the effects of smooth muscle (SM) activation has been made in canine carotid and iliac arteries. Measurements of external diameter and axial force were made on isolated cylindrical segments in response to internal pressure variations. Data were obtained during maximal norepinephrine (NE) and potassium (K) activation, and following metabolic inhibition of SM. These data were used to determine wall tangential stress-strain relations. The maximum increase in wall stress after K and after NE was greater for the iliacs and occurred at smaller values of wall strain. Passive stress-strain curves for the iliacs were likewise shifted to smaller strains, suggesting an important role of passive wall elements in setting the length of contractile elements. Diameter responses to K at low values of pressure were the same for iliacs and carotids, but were better maintained at higher pressure levels for the iliacs. Similar findings were found for iliac responses to NE and K. The results suggest that at low values of wall stress, active diameter responses are not strongly dependent on the maximum isometric stress development. However, higher pressure-diameter responses are also determined by the force-generating capacity of SM.

[1]  J G Llaurado,et al.  Collagen and Elastin Content in Canine Arteries Selected from Functionally Different Vascular Beds , 1966, Circulation research.

[2]  P. Dobrin,et al.  Influence of initial length on length-tension relationship of vascular smooth muscle. , 1973, The American journal of physiology.

[3]  R. Cox,et al.  Carotid artery mechanics, connective tissue, and electrolyte changes in puppies. , 1974, The American journal of physiology.

[4]  T. R. Hansen,et al.  Role of pressure in structural and functional changes in arteries of hypertensive rats , 1974 .

[5]  P. Hellstrand,et al.  The force-velocity relation in phasic contractions of venous smooth muscle. , 1975, Acta physiologica Scandinavica.

[6]  A. Rovick,et al.  Influence of vascular smooth muscle on contractile mechanics and elasticity of arteries. , 1969, The American journal of physiology.

[7]  B. Johansson.  Determinants of vascular reactivity. , 1974, Federation proceedings.

[8]  R. Speden,et al.  Constriction of Arteries at High Transmural Pressures , 1970, Circulation research.

[9]  P. Dobrin,et al.  Series Elastic and Contractile Elements in Vascular Smooth Muscle , 1973, Circulation research.

[10]  D. Bergel.  The static elastic properties of the arterial wall , 1961, The Journal of physiology.

[11]  R N Vaishnav,et al.  Nonlinear anisotropic elastic properties of the canine aorta. , 1972, Biophysical journal.

[12]  A. C. Burton,et al.  The reason for the shape of the distensibility curves of arteries. , 1957, Canadian journal of biochemistry and physiology.

[13]  P. Dobrin.  Isometric and isobaric contraction of carotid arterial smooth muscle. , 1973, The American journal of physiology.

[14]  D. Bohr.  Individualities among Vascular Smooth Muscles , 1965 .

[15]  R. Cox.  Three-dimensional mechanics of arterial segments in vitro: methods. , 1974, Journal of applied physiology.