Electro-Chemo-Mechanical Modeling of the Artery Myogenic Transient and Steady-State Response

Active contraction of smooth muscle results in the myogenic response and vasomotion of arteries, which adjusts the blood flow and nutrient supply of the organism. It is a multiphysic process coupled electrical and chemical kinetics with mechanical behavior of the smooth muscle. This paper presents a new constitutive model for the media layer of the artery wall to describe the myogenic response of artery wall for different transmural pressures. The model includes two major components: electrobiochemical, and chemomechanical parts. The electrochemical model is a lumped Hodgkin-Huxley-type cell membrane model for the nanoscopic ionic currents: calcium, sodium, and potassium. The calculated calcium concentration serves as input for the chemomechanical portion of the model; its molecular binding and the reactions with other enzyme cause the relative sliding of thin and thick filaments of the contractile unit. In the chemomechanical model, a new nonlinear viscoelastic model is proposed using a continuum mechanics approach to describe the time varying behavior of the smooth muscle. Specifically, this model captures the filament overlap effect, active stress evolution, initial velocity, and elastic recoil in the media layer. The artery wall is considered as a thin-walled cylindrical tube. Using the proposed constitutive model and the thin-walled equilibrium equation, the myogenic response is calculated for different transmural pressures. The integrated model is able to capture the pressure-diameter transient and steady-state relationship.