Role of myosin light chain kinase and myosin light chain phosphatase in the resistance arterial myogenic response to intravascular pressure.

The intrinsic ability of vascular smooth muscle cells (VSMCs) within arterial resistance vessels to respectively contract and relax in response to elevation and reduction of intravascular pressure is essential for appropriate blood flow autoregulation. This fundamental mechanism, referred to as the myogenic response, is dependent on apposite control of myosin regulatory light chain (LC(20)) phosphorylation, a prerequisite for force generation, through the coordinated activity of myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). Here, we highlight the molecular basis of the smooth muscle contractile mechanism and review the regulatory pathways demonstrated to participate in the control of LC(20) phosphorylation in the myogenic response, with a focus on the Ca(2+)-dependent and Rho-associated kinase (ROK)-mediated regulation of MLCK and MLCP, respectively.