Glycosaminoglycan secretion from perifused monolayer cultures of rabbit ear chondrocytes: Modification of xyloside effect by colchicine and cytochalasin B

Abstract

Chondrocytes isolated from elastic ear cartilage of young rabbits were grown in monolayer cultures. Secretion into the medium of glycosaminoglycans labeled with 35SO 4 was monitored by continuous perifusion. This experimental system was used to study the influence of colchicine, lumicolchicine, and cytochalasin B on the response to a 2-h β- d-xyloside pulse. In untreated cultures the stimulative effect of the xyloside was seen within 6 min and a new secretory steady state was reached in less than 20 min. Rabbit ear chondrocytes thus respond considerably faster to β- d-xyloside than chick sternum chondrocytes. After xyloside withdrawal glycosaminoglycan production decreased to baseline amounts in about 30 min. Colchicine caused a delayed and protracted response to xyloside. These effects were not mimicked by lumicolchicine. Hence, cytoplasmic microtubules appear to be involved in the secretion of glycosaminoglycans. On the other hand, colchicine had no effect on the size distribution of the labeled macromolecules. These findings suggest that colchicine exerts its action at a stage subsequent to initiation of the synthesis of glycosaminoglycans. Cytochalasin B did not affect the rate of response to xylside exposure or withdrawal.