Three methods for measuring the increase in the capacity of the distended biliary tree in the rat produced by α-naphthylisothiocyanate treatment

The capacity of the distended biliary tree was measured in each rat by three techniques referred to as retrograde-intrabiliary-injection (RII), segmented-retrograde-intrabiliary-injection (SRII), and retrograde-pushback (RPB). Control rats, receiving by gavage 0.2 ml of olive oil daily for 8 consecutive days, were found 15 days after treatment to have distended capacities of 33.4 ± 2.7, 34.1 ± 3.4, and 31.6 ± 2.9 μl (mean ± SE) as obtained by the RII, SRII, and RPB techniques, respectively. In another group of rats, treated for 8 consecutive days with α-naphthylisothiocyanate (ANIT) (45 mg/kg, po) in 0.2 ml of olive oil, the RII, SRII, and RPB techniques estimated distended biliary capacity 15 days after the last treatment to be 48.0 ± 1.6, 47.5 ± 1.4, and 46.8 ± 1.3 μl, respectively. In control animals the two-way analysis of variance showed no significant difference occurred between the three methods. For each of the three methods, the mean distended biliary tree capacity of the ANIT-treated rats was significantly greater than the control rats, p < 0.02. No significant difference was found between control and ANIT-treated rats for mean liver weights and bile flow rates. Thus, the increase in distended biliary capacity with ANIT treatment was not accompanied by any change in liver weight or bile flow rate.