Reduced effect of taxol on plasma protein secretion by developing rat liver.

The effect of taxol, a potent stabilizer of microtubules, on plasma protein secretion by slices prepared from mature and developing rat liver was determined. After 4 hr of incubation, taxol (50 microM) inhibited albumin secretion by only 10% on gestation Day 19, by 16% 4 days after birth, but by 40% in the adult. Inhibition of glycoprotein secretion by taxol was similar to that of albumin secretion at all ages studied. Combined with information obtained from previous investigations, the present study indicates that agents that either inhibit microtubular assembly or that stabilize microtubules both have a reduced capacity to inhibit hepatic protein secretion during development. These findings suggest that a reduced requirement for microtubular participation in protein secretion is present in developing liver.