Abstract
Phosphatases in rat thoracic aorta and cultured smooth muscle cells derived from the aorta have been investigated. In the present study, changes in the phosphatase activity of cultured smooth muscle cells with the passage and with the growth and the effect of change of medium on acid phosphatase activity were investigated.
Acid phosphatase activities of rat thoracic aorta and cultured smooth muscle cells in early passages (4-30) increased at pH 5.5, while those of cells in late passages (more than 100) increased at pH 3.5. This suggests that there may be two types of acid phosphatase. Although alkaline phosphatase activity of the intact aorta increased at pH 10.5, that of cultured cells was significantly weak at any alkaline pH.
Acid phosphatase activity expressed on the basis of protein content increased with the growth, while that expressed on the basis of cell number remained nearly constant.
Acid phosphatase activities of cells cultured for 1-2 days after change of medium were lower than those of cells cultured for the same period without change of medium. Of components present in the medium, serum was most effective for this reduction of enzyme activity.
