[35S]proteoglycan metabolism of arterial smooth muscle cells cultured from normotensive and hypertensive rats.

Arterial smooth muscle cells cultured from normotensive and hypertensive rats incorporated [35S]sulfate into the extracellular and pericellular sulfated proteoglycans and endocytose extracellular [35S]proteoglycans at a significantly higher rate in the phase of logarithmic growth than did nondividing cells. 35S incorporation into proteoglycans was positively correlated with [3H]thymidine incorporation into the cellular TCA-precipitable material. The rates of [35S]proteoglycan synthesis and endocytosis per cell pr day were higher in smooth muscle cells from hypertensive than from normotensive animals, the observed differences being related to a higher average protein content of smooth muscle cells cultured from hypertensive rats as compared with cells of normotensive animals. Gel filtration under dissociative conditions separated the [35S]proteoglycans into high and low molecular weight fractions (A, B) differing in glycosaminoglycan composition and their ability to be endocytosed by smooth muscle cells. The relative proportion of the high molecular weight proteoglycan fraction A decreased continuously from sparse to confluent cell cultures.