Transcytosis and paracellular movements of horseradish peroxidase across liver parenchymal tissue from blood to bile. Effects of alpha-naphthylisothiocyanate and colchicine

Abstract

The pathways for the entry of horseradish peroxidase (HRP) into bile have been investigated using the isolated perfused rat liver operating under one-pass conditions. Following a 1 min one-pass infusion of HRP, two peaks of HRP activity were noted in the bile. The first, at 5-7 min post-infusion, correlated with the biliary secretion of the [3H]methoxyinulin which was infused simultaneously with the HRP. The second peak of HRP activity occurred at 20-25 min, and correlated with the biliary secretion of 125I-IgA, which was also infused simultaneously with the HRP. If the isolated livers were perfused with a medium containing 2.5 microM-colchicine, the biliary secretion of IgA and the second secretion peak of HRP were inhibited by 60%. If rats were pretreated for 12h with alpha-naphthylisothiocyanate (25mg/100g body wt.) prior to liver isolation, the biliary secretion of [3H]methoxyinulin and the first secretion peak of HRP were increased. Taken together, these results suggest that HRP enters the bile via two routes. The faster route, which was increased by alpha-naphthylisothiocyanate and correlated with [3H]methoxyinulin entry into bile, was probably paracellular, involving diffusion across tight junctions. The slower route, which was inhibited by colchicine and correlated with the secretion of IgA, was probably due to transcytosis, possibly within IgA and other transport vesicles.

Fluid phase endocytosis by cultured rat hepatocytes and perfused rat liver: implications for plasma membrane turnover and vesicular trafficking of fluid phase markers.

“…Colchicine (10 uM), by contrast, as compared with lumicolchicine, decreased the rate of net inulin accumulation (P3, Function 1) by =55% and increased the steady-state value of the initial exponential component (presumably representing an increase in the apparent size of the rapidly turning-over pool), but it had no significant effect on the initial rate of inulin uptake. Similarly, in perfused liver, neither taurocholate nor chloroquine altered the biliary secretion of fluid phase markers (5, 14), whereas colchicine decreased the vesicular transport of fluid phase markers from perfusate to bile by 60-80% (5,14,15). Table 1).…”

Biliary lipid secretion in man

“…Direct evidence for a vesicular mechanism for bile acid transport involving the Golgi apparatus has been obtained using autoradiography [73,74] and antibodies directed against cholic and ursodeoxycholic acid conjugates on rat liver sections [75]. Such a transport system is probably too slow to account for the very rapid transcellular transport of bile acid [67,76]. Furthermore, the inhibitory effect ofcolchicine and vinblastine on bile acid secretion is less marked than for cholesterol and phospholipid secretion [65,77], and it is only observed at high bile acid secretion rates [77-791.…”

Inhibition of biliary cholesterol and phospholipid secretion by cefmetazole. The role of vesicular transport and of canalicular events

“…Horseradish peroxidase is a glycoprotein of 40 000 Da that has been found to be transferred into bile both by microtubulardependent and -independent vesicular pathways and by sieving through the tight junctions (Hayakawa et al, 1990;Kan et al, 1989;Lowe et al, 1985). In rats under basal conditions, the microtubule-dependent vesicular pathway accounts for 90 % of the biliary output (Hayakawa et al, 1990), and hence horseradish peroxidase is a useful tracer of vesicular transport in hepatocytes (Okanoue et al, 1984;Romain et al, 1990).…”