Localization of Calcium Pump Activity in Smooth Muscle

See allHide authors and affiliations

Science  26 Jan 1973:
Vol. 179, Issue 4071, pp. 384-386
DOI: 10.1126/science.179.4071.384


A microsomal fraction isolated from longitudinal smooth muscle of guinea pig ileum actively sequesters calcium ion in the presence of magnesium and adenosine triphosphate in a fashion previously described for microsomes of the rabbit aorta. This activity in guinea pig ileum appears to be associated primarily with the plasma membrane as is found in the red cell. By contrast the uptake of calcium in aortic smooth muscle appears to be associated to an appreciable extent with intracellular membranes, possibly analogous to the sarcoplasmic reticulum of skeletal muscle.