Biliary albumin excretion induced by bile salts in rats is a pathological phenomenon.
The bile to plasma 125I-albumin concentration ratio (B/P ratio) was examined before and during various bile salt infusions in male Wistar rats that had previously received iv injection of 125I-albumin. Endogenous rat albumin and IgG concentrations in the bile were also determined by a single radial immunodiffusion method. Taurocholate (TC) infusion (1.0 mumol/min/100 g body wt) significantly increased the bile flow rate in the first hr but the flow began to decline in the second hr. The B/P ratio as well as rat albumin (and IgG) excretion into the bile significantly increased as early as 15 min after the start of TC infusion, and the increase became more pronounced in the second hr, when the bile flow began to decrease. Infusion of taurochenodeoxycholate (TCDC, 0.4 mumol/min/100 g) caused a reduction in bile flow 15 min after the start of infusion but the B/P ratio increased 40 times at its peak compared with the basal value before the bile salt infusion. Simultaneous infusion of tauroursodeoxycholate (TUDC, 0.6 mumol/min/100 g) and TCDC not only abolished the cholestasis induced by TCDC but maintained stable choleresis as long as for 2 hr. During this choleretic period, the B/P ration never exceeded the basal value. The choleresis induced by either taurodehydrocholate (TDHC) or bucolome was not accompanied by enhanced albumin excretion. In rats given TDHC infusion, albumin excretion started to increase only after the bile flow began to decline following the initial choleretic period. The enhanced excretion of albumin induced by TC and TCDC is therefore suggested to be caused not by the choleresis per se but by a possible concomitant increase in the communication between sinusoids and bile canaliculi, which eventually leads to cholestasis. Our results suggest that the biliary excretion of albumin enhanced by bile salt infusion in rats is primarily the result of hepatocyte damage closely related to cholestasis rather than to choleresis, and that the rate of such excretion can be used as a convenient and reliable marker for hepatocyte damage.
Ohta
M
M
First Laboratory of Clinical Physiology, Tokyo Metropolitan, Institute of Gerontology, Japan.
Kitani
K
K
Kanai
S
S
D000418:Albumins / Q000378:metabolism*; D000818:Animals; D001646:Bile / Q000378:metabolism* / Q000502:physiology; D001647:Bile Acids and Salts / Q000494:pharmacology*; D007074:Immunoglobulin G / Q000378:metabolism; D007457:Iodine Radioisotopes; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013656:Taurocholic Acid / Q000494:pharmacology
D000418:Albumins; D001647:Bile Acids and Salts; D007074:Immunoglobulin G; D007457:Iodine Radioisotopes; D013656:Taurocholic Acid