The effects of acute renal failure on the pharmacokinetics of indocyanine green in the rat

Current and Potential Applications for Indocyanine Green in Liver Transplantation

Indocyanine green (ICG) is a fluorescent dye taken up and almost exclusively cleared by the liver. Measurement of its clearance and visualization of its fluorescence make it suitable for a number of potential applications in liver transplantation including assessment of liver function and real-time assessment of arterial, venous, and biliary structures. ICG clearance can be used to assess donor graft quality before procurement and graft metabolic function before transplant using normothermic ex vivo machine perfusion. ICG clearance in the post-liver transplantation period is able to predict recipient outcomes with correlations to early allograft dysfunction and postoperative complications. After absorbing light in the near-infrared spectrum, ICG also emits fluorescence at 835 nm. This allows the assessment of vascular patency after reconstruction and patterns of liver perfusion in real time. ICG perfusion patterns after revascularization are also associated with posttransplant graft function and survival. ICG fluorescence cholangiography is routine in a number of centers and acts as an aid to identifying the optimal point of bile duct division during living donor liver transplantation to optimize safety for both donor and recipient. In summary, ICG is a versatile tool and has a number of useful applications in the liver transplantation journey including assessment of liver function, perfusion assessment, and cholangiography. Further research and clinical trials are required to validate and standardize its routine use in liver transplantation.

Effect of glycerol-induced acute renal failure and di-2-ethylhexyl phthalate on the enzymes involved in biotransformation of xenobiotixs

The effects of di-(2-ethylhexyl)-phthalate (DEPH) on the levels of cytochrome P-450 and b5 monooxygenases were studied in the rat kidney and liver in acute renal failure induced by glycerol. Intramuscular injection of glycerol (50%,10 ml x kg(-1)) to rats produced proximal tubular damage and acute renal failure. The indicators of renal function, serum urea and creatinine significantly increased (480 and 350 percent, respectively). In control and glycerol-treated animals DEPH had no significant effect on the concentrations of serum urea and creatinine. Twenty-four hours after glycerol injection the total amount of cytochrome P-450 and b5 significantly decreased in renal but increased in liver microsomal fractions. Moreover, 48 and 72 hours after glycerol injection the level of cytochrome P-450 and b5 significantly increased in both organs. A single dose of DEPH (2 ml x kg(-1), i.p.) also elevated the total cytochrome P-450 and b5 in control animals. This enhancing effect of DEPH was additive to that of glycerol in glycerol-induced acute renal failure. These results indicate that DEPH and glycerol evoked pathological changes may affect the metabolism of xenobiotics plus endogenous hormones in the liver and in kidney.

Differential expression of renal adenosine A(1) receptors induced by acute renal failure

The distribution of renal adenosine A(1) receptors was investigated in rats with glycerol- or mercuric chloride (HgCl(2))-induced acute renal failure. Receptors were localised by autoradiography using [(3)H]8-cyclopentyl-1,3-dipropylxanthine ([(3)H]DPCPX), a selective A(1) adenosine receptor antagonist. In saline-injected control animals, significant labelling with [(3)H]DPCPX was detected in glomeruli, the inner stripe of outer medulla, and the inner medulla. Sixteen hours following induction of glycerol-induced acute renal failure (ARF), a 34% increase in labelling in glomeruli was noted compared to saline-injected controls, and by 48 hr, glomerular labelling had increased by 200%. In addition, 48 hr following glycerol injection, significant labelling was now detected in the cortical labyrinth and medullary rays whilst, in the inner medulla, labelling had decreased by 34%. By contrast to glycerol-induced ARF, the only significant change noted 48 hr following induction of HgCl(2)-induced ARF was a 39% decrease in labelling in the inner medulla. It is concluded that glycerol-induced ARF results in differential expression of renal adenosine A(1) receptors with increased expression in the cortex and reduced expression in the inner medulla. Increased density of A(1) receptors in glomeruli may account, at least in part, for the increased renal vasoconstrictor response to adenosine and depressed glomerular filtration rate noted previously in this type of acute renal failure.

Effect of acute renal failure on the disposition of cefoperazone

The effect of acute renal failure on the disposition of cefoperazone was investigated. Rats, 3 days after uranyl nitrate treatment, were used to model acute renal failure. Although plasma-protein binding of cefoperazone decreased significantly in acute renal failure compared with control rats, the plasma clearance of total (bound plus unbound) drug after intravenous administration (50 mg kg(-1)) did not differ significantly between the two groups (5.61+/-2.37 mL min(-1) for control and 4.75+/-2.82 mL min(-1) for acute renal failure). Consequently the plasma clearance of the unbound drug in acute renal failure (6.14+/-1.16 mL min(-1)) was significantly lower than in control rats (15.6+/-3.7 mL min(-1), P < 0.025). Plasma clearance of the drug (both total and unbound) was also dependent on bile flow, and clearance of the unbound drug in acute renal failure rats was lower than in control rats with identical bile flow rates. To examine the mechanism of reduced unbound cefoperazone clearance, an in-vitro experiment using a simultaneous perfusion system of rat liver and kidney was performed. By changing perfusate plasma protein from bovine serum albumin to human serum albumin, the plasma clearance of the total cefoperazone changed to one-sixth in proportion to the unbound cefoperazone in the perfusate plasma. On the other hand, the plasma clearance of the total and unbound drug in acute renal failure rats decreased significantly compared with controls. These results demonstrate that the plasma clearance of unbound cefoperazone, which is mainly eliminated by the liver, decreased in acute renal failure in rats, probably due to changes in hepatic transport.

Renal adenosine A1 receptor binding characteristics and mRNA levels during the development of acute renal failure in the rat

1. The binding characteristics and mRNA levels for renal adenosine A1 receptors were investigated in normal rats and rats with acute renal failure (ARF) induced by either glycerol or HgCl2. 2. Saturation isotherms determined from the binding of [3H]-1,3-dipropyl-8-cyclopentylxanthine ([3H]-DPCPX), a selective adenosine A1 antagonist, to renal membranes of untreated rats gave values of 0.62 nM for the equilibrium dissociation constant (Kd) and 19.9 fmol mg-1 protein for the density of binding sites (Bmax). No saturable binding was observed with [3H]-2-(p-(carboxylethyl)-phenylethylamino)-5'-N-ethylcar box amido adenosine ([3H]-CGS 21680), a selective adenosine A2a agonist. 3. By contrast to time-matched controls, renal membranes obtained from rats 16 and 48 h following the induction of ARF with glycerol, showed statistically significant increases (2-4 fold) in both Bmax and Kd for the binding of [3H]-DPCPX. No significant changes in the binding characteristics of [3H]-DPCPX were noted with membranes from rats 48 h following the production of ARF with HgCl2. 4. Adenosine A1 receptor mRNA levels were significantly elevated 0.5, 16 and 48 h following induction of ARF with glycerol, whilst no change was noted in mRNA levels for beta-actin at the same time points. No statistically significant changes in adenosine A1 receptor or beta-actin mRNA levels were noted 48 h after the induction of ARF with HgCl2. 5. This study indicates that glycerol-induced ARF in the rat is associated with an increase in renal adenosine A1 receptor density which appears to result from increased transcription of the gene for this receptor. An increase in adenosine A1 receptor density in renal resistance vessels may explain, at least in part, the enhanced renal vasoconstrictor response to adenosine in glycerol-induced ARF that was noted in a previous study.

Further characterization of the protective effect of 8-cyclopentyl-1,3-dipropylxanthine on glycerol-induced acute renal failure in the rat

In the rat, treatment with the alkylxanthine 8-cyclopentyl-1,3-dipropylxanthine (CPX) at a dose of 0.1 mg kg-1 antagonizes adenosine-induced falls in renal blood flow and reduces the severity of glycerol-induced acute renal failure. Treatment of glycerol-injected rats with 0.03 mg kg-1 of CPX resulted in no significant improvements in a range of indices of renal function. However, treatment with 0.1 or 0.3 mg kg-1 doses of CPX did significantly ameliorate acute renal failure although there were no significant differences in the degree of protection of renal function afforded by these two doses. In glycerol-injected rats, 0.1 or 0.3 mg kg-1 CPX administered either as a single dose or repeated doses every 12 h for two days did not inhibit renal phosphodiesterase. Thus the beneficial effects of CPX can be produced by doses that have no effect on renal phosphodiesterase activity whereas 0.1 mg kg-1 of CPX has been shown previously to antagonize the actions of adenosine. The findings provide further evidence that the beneficial effect of CPX in glycerol-induced acute renal failure is a consequence of adenosine antagonism and not phosphodiesterase inhibition.

Theophylline neurotoxicity is unaffected by glycerol-induced renal failure

Glycerol acute renal failure (ARF) was examined to see if it alters theophylline (Th) neurotoxicity in rats. Concentrations of Th in serum, cerebrospinal fluid and in brain at seizure onset were similar in control and ARF rats infused with Th. Thus, glycerol ARF fails to alter Th neurotoxicity, an effect similar to that noted previously with uranyl nitrate but not with ureter ligation.

Amelioration of glycerol-induced acute renal failure in the rat with 8-cyclopentyl-1,3-dipropylxanthine

1. Previous studies have shown that 8-phenyltheophylline (8-PT), a non-selective antagonist at adenosine A1- and A2-receptors, can ameliorate the severity of glycerol-induced acute renal failure (ARF) in the rat. In the present study we have examined the effects of an antagonist with selectivity for adenosine A1-receptors (8-cyclopentyl-1,3-dipropylxanthine, CPX) on the development of ARF. 2. In the anaesthetised rat 8-PT (4 mg kg-1, i.v.) and CPX (0.1 mg kg-1, i.v.) antagonised adenosine-evoked responses which are thought to be mediated via A1-receptors (bradycardia and decrease in renal blood flow). The agonist dose-ratio produced by CPX was equal to or greater than that found with 8-PT (heart rate and renal blood flow respectively). The hypotensive response to adenosine which is predominantly due to A2-receptor activation was also antagonised by 8-PT, whereas CPX was a much less effective antagonist of this response. 3. Administration of CPX (0.1 mg kg-1, i.v.; twice daily for two days) significantly attenuated the increase in plasma levels of urea and creatinine, the increased kidney weight and the renal tubule damage observed in rats 2 days following induction of ARF with intramuscular glycerol injection. In addition treatment with CPX significantly enhanced the clearances of inulin and p-aminohippurate. 4. After glycerol injection, the mortality rate over 7 days in untreated and vehicle-treated rats was 43% and 21% respectively. In contrast, all animals treated with CPX survived over the 7 day observation period. 5. These results support the suggestion that adenosine is an important factor in the development of ARF and indicate that this effect of the purine is likely to be mediated via an adenosine A1-receptor.

Amelioration of glycerol-induced acute renal failure in the rat with 8-phenyltheophylline: timing of intervention

The importance of timing and duration of 8-phenyltheophylline (8-PT) administration in determining its beneficial action in glycerol-induced acute renal failure (ARF) was investigated by examining the effects of a single dose of 8-PT given immediately following (0 h) glycerol injection and at 1 and 3 h after glycerol injection. 8-PT when given at 0 h significantly lowered plasma urea and creatinine concentrations and significantly increased inulin clearance when compared both to untreated animals and those that received the vehicle for the drug. By contrast, 8-PT when administered at 1 h afforded no protective effect on renal function and, when injected at 3 h, the only significant effect was lowered plasma creatinine levels when compared to untreated rats; at this latter time it did not lower plasma urea levels or improve inulin clearance. None of the 8-PT injections attenuated the increase in kidney weight associated with ARF or reduced the kidney damage as assessed by histological examination. The results show that a single administration of 8-PT made immediately following glycerol injection can ameliorate the biochemical and functional indices of impaired renal function, but does not produce an improvement in kidney morphology.

Dibromosulphophthalein: its pharmacokinetics and binding to hepatic cytosol proteins in rats with acute renal failure

1. The pharmacokinetics, biliary excretion and binding of dibromosulphophthalein (DBSP) to plasma proteins and hepatic cytosol proteins have been studied in male rats with glycerol-induced acute renal failure (ARF). 2. The rate constants for hepatic uptake, efflux from liver to plasma and excretion into bile were all significantly decreased in rats with ARF. Furthermore, the plasma clearance of DBSP was also reduced. 3. The initial (0-10 min) and maximum biliary excretion rates of DBSP were both diminished in animals with ARF. The maximum excretion rate occurred between 5-10 min in control rats and 10-15 min in rats with ARF. However, there was no statistically significant change in the percentage dose recovered from bile after 30 min. 4. The plasma-protein binding of DBSP was decreased in rats with ARF and this change was due to a significant reduction in the association constant for the primary binding sites. 5. The binding of DBSP to ligandin (Y protein) was reduced by about 38% in rats with ARF but no change was noted in binding to Z protein. Reduced binding to ligandin was accompanied by decreased total liver glutathione S-transferase (GST) activity and a 36% reduction in the GST activity of ligandin. 6. The results support the contention that altered hepatic handling of cholephilic dyes in rats with ARF may be due to reduced binding to ligandin.

Effect of 8-phenyltheophylline, enprofylline and hydrochlorothiazide on glycerol-induced acute renal failure in the rat

The adenosine antagonist 8-phenyltheophylline (8-PT) is a diuretic in normal rats and can ameliorate glycerol-induced acute renal failure (ARF) in this species. To define which action of 8-PT is important in its salutary effect in ARF, we have compared its effects with those of enprofylline (a xanthine with little affinity for adenosine receptors) and with those of the tubular diuretic hydrochlorothiazide. In one series of experiments, groups of rats with ARF of 24 h duration were given a single dose of drug or vehicle. Only 8-PT enhanced urine volume when compared with the vehicle-treated group. In a second set of experiments, groups of glycerol-injected rats received drug or vehicle treatment (i.p.) twice daily for 2 days. Rats which received a course of 8-PT treatment had significantly lower plasma urea and creatinine concentrations, a higher glomerular filtration rate, a lower kidney weight and improved kidney morphology when compared with vehicle-treated rats. The only beneficial effect noted after enprofylline treatment was an improved kidney morphology. Hydrochlorothiazide treatment compared with vehicle treatment did not ameliorate any index of renal function but resulted in significant elevations in plasma urea and creatinine levels. The inability of enprofylline or hydrochlorothiazide to mimic the effects of 8-PT in ARF indicate that the effects of 8-PT are probably associated with adenosine receptor blockade and not with a tubular diuretic action.

Pharmacokinetics and biliary excretion of rose bengal in rats with acute and chronic renal failure

The effects of glycerol-induced acute renal failure (ARF) and surgically induced chronic renal failure (CRF) on the pharmacokinetics and biliary excretion of rose bengal have been examined in the rat. Both the pharmacokinetics and biliary excretion of rose bengal were unaltered in either ARF or CRF. The latter results in CRF contrast with those of Tse et al (1976, Int. J. Nucl. Med. Biol. 3: 134-137) who reported decreased removal of the dye from blood and reduced biliary excretion. In addition, rose bengal behaves differently from bromosulphophthalein and indocyanine green whose hepatic uptake and initial biliary excretion are known to be decreased in ARF. The results suggest that rose bengal may have a hepato-biliary transport route which differs from that of bromosulphophthalein and indocyanine green, and the findings also emphasize the selective nature of altered organic anion uptake by the liver in ARF.

Effect of the adenosine antagonist 8-phenyltheophylline on glycerol-induced acute renal failure in the rat

8-Phenyltheophylline (8-PT)(10 mg kg-1) or its vehicle(1 ml kg-1) were administered intravenously or intraperitoneally twice daily over 48 h to rats with acute renal failure (ARF) induced by intramuscular (i.m.) injection of glycerol. Rats treated with 8-PT i.v. had significantly lower plasma urea and creatinine levels at 24 and 48 h compared to untreated animals. The vehicle also reduced plasma urea and creatinine when compared to untreated controls. However, plasma urea levels in 8-PT-treated rats were significantly lower than in vehicle-treated animals at 24 and 48 h after both i.v. and i.p. administration. Plasma creatinine concentrations also tended to be lower in the 8-PT-treated group. [3H]-inulin clearance at 48 h after i.m. glycerol was significantly greater in rats dosed i.p. with 8-PT compared to either untreated or vehicle treated rats. Examination of kidneys taken from rats 48 h after i.m. glycerol showed that 8-PT treatment significantly reduced renal damage and kidney weight compared to the untreated or vehicle-treated groups. In a 7 day study all the rats which received 8-PT i.p. survived whilst in the vehicle and untreated groups the mortality rates were 12 and 21% respectively. In a separate series of experiments 8-PT (10 mg kg-1, i.v. or i.p.) was found to antagonize adenosine-induced bradycardia in conscious rats for up to 5 h. There is no clear explanation for the partial protection afforded by the vehicle but it may be related to either its alkalinity or an osmotic effect produced by the polyethylene glycol component. 9 The protective effect of 8-PT in rats with ARF was probably the result of adenosine antagonism.

Relation between renal and hepatic excretion of drugs: I. Phenol red in comparison with p-aminohippurate and indocyanine green

Phenol red is a suitable compound for the simultaneous assay of renal and hepatic excretion in the rat. Its elimination has been compared with those of p-aminohippurate (PAH) and indocyanine green (ICG) which are eliminated nearly exclusively via kidneys or liver, respectively. The interruption of one elimination route one day before the experiment, that means bile duct ligation (DL) in the case of ICG or bilateral nephrectomy (NX) in the case of PAH are followed by a slight increase in the elimination via the alternative pathway, but no effective compensation occurs. On the other hand, the renal excretion of phenol red is significantly increased after DL only following administration of high doses. This intensification is caused by an increase in the unbound amount of phenol red depending on the plasma concentration and reflects an enhanced glomerular filtration fraction. The biliary excretion increases significantly after NX, but only after infusion of low doses. The maximal biliary secretion capacity cannot be exceeded following NX, either. The competitive inhibition of phenol red excretion by probenecid supports the findings of NX or DL experiments. An influence of the three test substances on arterial blood pressure has been excluded. The most important factors influencing the switch over from one to the other elimination route seem to be at least in the case of phenol red the amount of unbound substance, the influence of the administered dose on the glomerular filtration, and disturbances in the volume of distribution, e.g. the possible reduction of hepatic uptake after DL.

Pharmacokinetics and biliary excretion of bromosulphophthalein, [3H]-ouabain and [3H]-taurocholic acid in rats with glycerol-induced acute renal failure

The pharmacokinetics and biliary excretion of bromosulphophthalein (BSP), ouabain and taurocholic acid (TChA) have been studied in rats with glycerol-induced acute renal failure (ARF). In rats with ARF, the hepatic uptake and initial biliary excretion of BSP were decreased. In addition, the rate of BSP conjugation with glutathione by rat liver homogenates was also decreased. This latter change may contribute to the initial decrease in the biliary excretion of BSP. No change was found in the hepatic uptake and biliary excretion of ouabain, but the area under the concentration-time curve was increased and the plasma clearance (Clp) decreased in rats with ARF. This decrease in Clp was not due to reduced renal excretion. The decreased Clp of ouabain in rats with ARF may come from reduced tissue binding and a concomitant decrease in its volume of distribution (Vd). The hepatic handling of TChA appeared unaltered in ARF, but the rate constant for the terminal part of the concentration-time curve (beta) was decreased. This change probably resulted from a large increase in Vd in rats with ARF. It is concluded that the decreased uptake of BSP was not due to a non-specific disturbance of hepatocyte function in ARF because the hepatic handling of ouabain and TChA were unaltered.

The plasma clearance of indocyanine green in rats with acute renal failure: effect of dose and route of administration

The pharmacokinetics of various doses (1-7.5 mg/kg i.v.) of indocyanine green (ICG) have been studied in control rats and rats with glycerol-induced acute renal failure (ARF). The pharmacokinetic changes seen at a dose of 1 mg/kg, after jugular vein administration, were significant decreases in uraemic rats in the rate of entry of ICG into the liver (k12) and in the rate of movement of dye from liver to plasma (k21). Greater and more numerous changes in pharmacokinetic parameters were recorded in experiments conducted using 4.0 and 7.5 mg/kg ICG. The results from these experiments showed that in addition to significant decreases in k12 and k21 there was a significant reduction in the rate constant for transfer of dye from liver to bile (k23). These changes were accompanied by a significant decrease in plasma clearance. In a separate series of experiments steps were taken to reduce the degree of uraemia produced by glycerol injection. The findings from these experiments showed no significant pharmacokinetic differences between control and mildly uraemic animals after administration of a dose of 7.5 mg/kg ICG. This suggests that the kinetic changes described above were a consequence of renal failure and not a direct hepato-toxic effect of glycerol.

Drug-protein conjugates--IV. The effect of acute renal failure on the disposition of [14C]captopril in the rat

The effect of acute renal failure (ARF) on the metabolism and covalent binding to plasma proteins (PP) of [14C]captopril [( 14C]CP) was investigated in the Wistar rat in vivo and in vitro using human and rat plasma. In the rat, ARF was induced by parenteral administration of glycerol. Glycerol-induced ARF markedly reduced the renal excretion of [14C]CP, the major route of elimination of the drug in control rats, but did not alter the plasma clearance of [14C]CP. However, there was a significant increase in the plasma concentrations of [14C]CP mixed disulphides with glutathione, cysteine and PP. The increase in mixed disulphide formation did not result in an increase in the concentration of radioactivity in the lung, liver, kidney, spleen or bile. Thus, control rats excreted 9.64 +/- 4.24% of the dose into bile in 3 hr while rats with ARF excreted 7.14 +/- 2.46%. In vitro, [14C]CP reacted rapidly with human or rat plasma to form mixed disulphides with endogenous thiols and PP. With uraemic plasma, there was a significant decrease in the amount of [14C]CP covalently bound to PP from both man and the rat.