ABSTRACT
In addition to their role in producing changes in mechanical tone, smooth muscle cells can perform other important functions such as cytokine production, migration, proliferation, and even antigen presentation. However, most of the clinically important pulmonary vascular pathologies involve defects pertaining to the contractile state of the smooth muscle; examples of this include hypoxic pulmonary vasoconstriction and ventilation-perfusion mismatching as well as pulmonary hypertension. Ionic mechanisms play key roles in many aspects of pulmonary vascular biology; this is particularly true of contraction and relaxation. Other authors in this volume will expound on each of the different ion channels and ionic mechanisms in the pulmonary vasculature. The purpose of the current chapter is to put these channels and mechanisms into the general perspective of excitationcontraction coupling.
