title: Role of calcium ion in maintenance of vascular smooth muscle tone.
abstract: Recent evidence indicates that vascular smooth muscle tone can be increased either by increasing cytoplasmic calcium ion (Ca++) levels or by increasing the sensitivity of the contractile apparatus to calcium. Data obtained with both luminescent and fluorescent calcium indicators indicate that the amount of force produced at a specific Ca++ is variable in intact vascular smooth muscle. Data obtained with the luminescent calcium indicator aequorin indicate that the calcium force curve is very steep in intact vascular smooth muscle cells; i.e., small changes in Ca++ can cause large changes in vascular tone. Therapeutic agents designed to directly decrease intrinsic myogenic tone could be designed to either decrease Ca++ or to decrease the sensitivity of the contractile apparatus to calcium. Considerable selectivity might be obtained by the latter approach.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
chemical_list: D002118:Calcium