Differential Colchicine Effects on the Transport of Membrane and Secretory Proteins in Rat Hepatocytes In Vivo : Bipolar Secretion of Albumin

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Abstract
We carried out a comparative investigation on the effects of colchicine (25 μmoles/100 gm body wt) on the intracellular transport, processing and discharge by secretion or proteolytic processing of a membrane protein (i.e., the polymeric IgA receptor) and a secretory protein (i.e., albumin) in rat hepatocytes. The results obtained indicated the following: (a) the transport and processing of polymeric IgA receptor is strongly inhibited and delayed, but the appearance of secretory component in the bile is not arrested; (b) polymeric IgA receptor reaches the sinusoidal plasmalemma in colchicine–treated specimens, as it does in controls; (c) albumin discharge into the plasma is strongly inhibited and markedly delayed in colchicinetreated as compared with control animals; (d) the reverse applies for albumin secretion in the bile, which is increased by a large factor; (e) newly synthesized albumin secreted directly from hepatocytes in control and in colchicine–treated animals is the major source of bile albumin; and (f) colchicine affects in different ways the polymeric IgA receptor and albumin arrival at the sinusoidal front and especially at the biliary front of the hepatocyte. (Hepatology 1992;15:714-721).