Quantitative biochemical and ultrastructural studies of microtubules in rat liver during the acute inflammatory reaction

Abstract

Quantitative biochemical and ultrastructural studies of liver microtubules were made in the rat during the acute inflammatory reaction, to determine whether microtubules play any part in hepatic secretion of plasma proteins. At various times during the reaction, total, free, and polymerized liver tubulin were estimated by the [ 3H]colchicine-binding assay, and the volume density of hepatocyte microtubules was measured by ultrastructural morphometry in the endoplasmic reticulum, the Golgi complex, and the sinusoidal areas of the cytoplasm, all three chosen for their involvement in protein secretion. Biochemical results indicated that hepatic polymerized tubulin rose during the acute inflammatory reaction, to a maximum of +58% compared to control rats, 24 hr after the beginning of the reaction. At that time, microtubule morphometry showed that microtubule volume density did not change in the endoplasmic reticulum but increased by 48% compared to control rats in the sinusoidal area; the volume of microtubules also rose in the Golgi area, allowing for the Golgi complex hypertrophy which occurred during the inflammatory reaction. The above observations demonstrate that during this reaction, additional microtubules are formed in the liver cells. They also indicate that the appearance of these additional microtubules might be connected with the enhanced hepatic plasma protein secretion which occurs during the acute inflammatory reaction.