593
`© 1983 J. Pharm. Pharmacol.
`J. Pharm. Pharmacol. 1983, 35: 593-594
`Communicated January 25, 1983
`Pharmacokinetics of indocyanine green in rats
`with chronic renal failure
`
`COMMUNICATIONS
`
`MICHAEL S. YATES, JANE EMMERSON, CHRISTOPHER J. BOWMER*, Department of Pharmacology, Medical & Dental Building,
`University of Leeds, Leeds LS2 9JT, U.K.
`
`Indocyanine green (ICG) is commonly used to assess
`liver function in man and animals. This dye has proved
`useful in previous investigations of liver function in rats
`with acute renal failure (Bowmer et a! 1982, 1983).
`Those studies showed that the hepatic uptake, plasma
`clearance and initial biliary excretion of ICG were all
`decreased in acutely uraemic rats. There is evidence
`that these aspects of liver function are also altered in
`rats with chronic renal failure (CRF), as Tse eta! (1976)
`reported that the plasma disappearance and biliary
`excretion of rose bengal were both decreased in rats
`with CRF. We therefore set out to find out if the kinetics
`of ICG are also altered in CRF and to compare any
`changes with those in rats in acute renal failure.
`
`Materials and methods
`Male Wistar rats (100-150 g) were partially (five(cid:173)
`sixths) nephrectomized; two thirds of the right kidney
`was removed at the first operation and one week later
`the left kidney was removed (Young et al1973). Sham
`operations, where the kidneys were exposed and the
`capsule removed, were performed on a control group of
`rats. The animals were studied 28 days after the
`completion of surgery.
`Rats were anaesthetized with pentobarbitone (60 mg
`kg-1, i.p.) and cannulae inserted into the trachea, left
`jugular vein and right carotid artery. ICG {Hynson,
`Wescott and Dunning Ltd., Baltimore) was injected via
`the jugular vein as an aqueous solution {7·5 mg kg-1, 10
`mg ml-1). Blood samples {0·1 ml) were taken from the
`carotid artery 1, 3, 5, 7, 10, 15, 20, 30, 40,50 and 60 min
`after dosing. The plasma concentration of ICG was
`measured spectrophotometrically at 800 nm {lga et a!
`1980) and plasma urea concentrations were measured
`by reaction with diacetyl monoxime (Bowmer et a!
`1982).
`Pharmacokinetic calculations were done on the basis
`of a two compartment model with elimination of ICG
`from the peripheral compartment (Bowmer et al1982).
`Results are expressed as mean ± s.d. and statistical
`comparison was made by the non-paired Student's
`t-test.
`
`Results
`There was no significant difference in mean body weight
`between rats intended for sham operation (141 ± 12 g)
`and those about to undergo partial nephrectomy (135 ±
`13 g). However, 28 days after surgery the partially
`• Correspondence.
`
`nephrectomized rats had a significantly lower (P < 0·01)
`mean body weight than the controls {Table 1). By
`contrast, wet liver weight, as a fraction of body weight,
`was significantly greater (P < 0·01) in the partially
`nephrectomized rats {Table 1). This difference was
`probably related to the difference in body weights
`because mean liver weights when not expressed as a
`fraction of body weight were not significantly different
`between controls {12·85 ± 0·85 g; n = 7) and uraemics
`{12·06 ± 0·84 g; n = 7). The partially nephrectomized
`rats showed evidence of having developed chronic renal
`failure, namely increased plasma urea concentrations
`and a significantly decreased (P < 0·001) packed cell
`volume (PCV) {Table 1).
`The effect of chronic renal failure on the plasma
`concentration-time data for ICG is shown in Fig. 1.
`Mean plasma concentrations of ICG in the period of 5 to
`20 min after administration were significantly greater in
`the uraemic rats than in controls. The pharmacokinetic
`parameters obtained from these data showed a signifi(cid:173)
`cantly prolonged ex-phase half-life; significant decreases
`in the rate constants for the entry of ICG into the liver,
`k12, and reflux from liver to plasma, k21 , and the plasma
`clearance, Clp, of ICG in the uraemic rats (Table 2).
`There was no statistical difference in the ~-phase
`half-life; the elimination rate constant, k23 ; the apparent
`volume of distribution, Vdss, and the apparent volume
`of the central compartment, Vc, between control and
`uraemic rats.
`
`Discussion
`Twenty-eight days after partial nephrectomy, the rats
`had developed a significant degree of chronic renal
`failure. In these animals there were substantial dec(cid:173)
`reases in the rate constants for entry of ICG into the
`liver, k12 , and reflux from liver to plasma, k21 • The
`
`Table 1. Body weight, liver weight, packed cell volume
`(PCV) and plasma urea concentration in rats with partial
`nephrectomy and sham-operated controls. t
`
`Body weight (g)
`Liver weight (g/100g)
`PCV(%)
`Plasma urea (mg/100 ml)
`
`Sham-operated
`control rats
`n=7
`341 ± 32
`3-68 ± 0·27
`48 ± 3
`49 ± 12
`
`Rats with
`partial nephrectomy
`n=7
`302 ± 22**
`4·00 ± 0·14**
`42 ± 2•••
`135 ± 26***
`
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`594
`
`300
`
`COMMUNfCA TIONS
`
`failure on
`renal
`Table 2 Effect of chronic
`pharmacokinetics of ICG (7·5 mg kg-1) in male rats.t
`
`the
`
`Phannacokinetic
`parameters
`
`to.s<>(m!nl
`to.s~(mm
`k~2 ~min- 1
`k21 mm-1
`k23 min-1
`Vc ml)
`Vdss(ml)
`Clp (ml min-I )/100g)
`
`Control rats
`(n=7)
`2·1 ± 0·3
`34 ± 1
`0·33 ± 0·05
`0·0069 ± 0·0009
`0·021 ± 0·003
`10± 1
`128±17·7
`0·71 ± 0·09
`
`Uraemic rats
`(n=7)
`2·9 ± 0·3***
`41 ± 12
`0·24 ± 0·03***
`0·0054 ± 0·0007* ••
`0·018 ± 0·004
`9·9 ± 1·2
`111 ± 21
`0·60 ± 0·07**
`
`40
`
`50
`
`10
`
`30
`20
`Time(min)
`FIG. 1. Plasma concentrations of ICG (7·5 mg kg-' i.v.) in
`male control (sham-operated) rats 0 and male rats with
`surgically-induced chronic renal failure e. Each point is
`the mean ± s.d. of seven rats. •p <0·05; ••p <0·01;
`••• P <0·001 relative to respective control value.
`
`decrease in k12 suggests that the hepatic uptake of ICG
`is impaired in rats with CRF. As ICG is exclusively
`removed from plasma by the liver (Cherrick et al1960;
`Leevy et al1963) and there was no significant change in
`Vdss, the decrease in k12 was probably responsible for
`the reduced plasma clearance of ICG in the uraemic
`rats.
`The results are similar to those obtained for ICG in
`rats with glycerol-induced acute renal failure (Bowmer
`et al1982). In that model of acute renal failure k12 , k21
`and the plasma clearance of ICG were all decreased in
`acutely uraemic rats. The elimination rate constant, k23 ,
`was also decreased; but only the initial biliary excretion
`(during the first 10 min collection) was reduced, overall
`biliary excretion remained unchanged (Bowmer et a!
`1983). In rats with CRF k23 was not significantly altered
`and, together with observations on rats with acute renal
`failure, this suggests that the overall biliary excretion of
`ICG is unlikely to be affected in rats with CRF.
`The altered kinetic behaviour of ICG is consistent
`with changes found in CRF for other dyes used to assess
`liver function. Tse eta! (1976) found that the clearance
`of rose bengal from blood is decreased in chronically
`uraemic rats and the hepatic uptake of bromosulphoph(cid:173)
`thalein is decreased in patients with CRF (Wernze &
`Spech 1971). This consistency of altered kinetic behavi(cid:173)
`our is not unexpected as these dyes inhibit each other's
`uptake into the liver (Hunton et al1961; Scharschmidt
`et al1975; Schwenk et al1976), bind to similar hepatic
`cytoplasmic proteins (Levi et a! 1969; Klassen 1976),
`and so may share common mechanisms for uptake into
`and storage within the hepatocyte.
`
`Our results provide little insight into the mechanism
`of CRF-induced changes of hepatic uptake. However,
`Wernze & Spech (1971) suggested that altered hepatic
`protein metabolism may be responsible. Renal failure
`can induce changes in protein metabolism (Knochel &
`Seldin 1976) and ICG, rose bengal and bromosulphoph(cid:173)
`thalein bind avidly to hepatic cytoplasmic proteins (Levi
`et al1969; Klassen 1976). Alteration in the intracellular
`concentration of these proteins could possibly alter the
`influx of their ligands into the hepatocyte.
`
`We would like to thank the Wellcome Trust for its
`financial support.
`
`REFERENCES
`Bowmer, C. J., Yates, M. S., Emmerson, J. (1982)
`Biochem. Pharmacol. 31: 2531-2538
`Bowmer, C. J., Emmerson, J., Yates, M.S. (1983) Ibid. in
`the press
`Cherrick, G. R., Stein, S. W., Leevy, C. M., Davidson,
`C. S. (1960) J. Clin. Invest. 39: 592-600
`Hunton, D. B., Bollman, J. L., Hoffman, H. N. (1961)
`Ibid. 40: 1648-1655
`Iga, T., Yokota, M., Sugiyama, Y., Awazu, S., Hanano,
`M. (1980) Biochem. Pharmacol. 29: 1291-1297
`Klassen, C. D. (1976) Toxicol. Appl. Pharmacol. 38:
`85-100
`Knochel, J.P., Seldin, D. W. (1976) in: Brenner, B. M.,
`Rectar, F. C. (eds) The Kidney. Vol. 2, W. B. Saunders
`& Co., Philadelphia, Chapter 34
`Leevy, C. M., Bender, J., Silverberg, M., Naylor, J. (1963)
`Ann. N.Y. Acad. Sci. 111: 161-175
`Levi, A. J., Gatmaitan, Z., Arias, I. M. (1969) J. Clin.
`Invest. 48: 2156-2167
`Scharschmidt, B. F., Waggoner, J. G., Berk, P. D. (1975)
`Ibid. 56: 1280-1292
`Schwenk, M., Burr, R., Schwarz, L., Pfaff, E. (1976) Eur.
`J. Biochem. 64: 189-197
`Tse, J. W., Wiebe, L. 1., Ediss, C., Shysh, A. (1976) Int. J.
`Nucl. Med. Bioi. 3: 134-137
`Young, G. A., Anderson, C. K., Parsons, F. M. (1973) Br.
`J. Exp. Pathol. 54: 241-248
`Wernze, H., Spech, H. J. (1971) Klin. Wschr. 49:
`1318-1322
`
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