Clearance and elimination of 125I-Rose Bengal in the sub-totally nephrectomized chronically uremic rat

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.

Host immune status in uremia. V. Effect of uremia on resistance to bacterial infection

Infection is a frequent complication and cause of death in renal failure. Although it is widely accepted that uremia has an adverse effect on host resistance to infectious disease, this association has not been proven. In the present experiments, the relationship between uremia and susceptibility to infection has been investigated using an animal model of chronic, severe uremia. Lung infections (using Pseudomonas aeruginosa and Klebsiella pneumoniae), bacteremia, peritonitis and subcutaneous infection (using Escherichia coli) were induced in uremic and normal rats and the course of infection compared. The ability of the uremic host to clear Ps. aeruginosa from the lung was marginally impaired in the first 24 hr after the challenge but was normal in the later stages of the infection. Similarly, in the bacteremia study, secondary invasion of the lungs by several other species of bacteria occurred in 33% of the uremic animals. We found no other evidence of impairment of immunity in uremia in the infections that we studied and, taken overall, the results support arguments that uremia per se is unlikely to be an important factor predisposing patients with renal failure to infection.

Host immune status in uremia. IV. Phagocytosis and inflammatory response in vivo

Infection is a frequent complication and cause of death in renal failure, but the association between uremia, depressed immune status, and susceptibility to infection is far from proven. In the present studies, the effect of uremia on the inflammatory response and phagocytic ability was investigated in an animal model. The inflammatory response, as measured by the ability of leukocytes to mobilize into subcutaneous implanted sponges, was impaired at 6 hr but was normal 24 hr after implantation. The peripheral blood response of uremic animals to the leukocytosis promoting protein from Bordetella pertussis was similar to that of control animals. Reticuloendothelial clearance of labelled albumin was unimpaired but catabolism of this substance was reduced significantly in uremic animals. The ability of the uremic host to clear an intravenous challenge of virus was also depressed. Phagocytic and bactericidal capability of polymorphonuclear (PMN) leukocytes, measured in vitro by latex ingestion and phagocytosis and killing of Staphylococcus aureus, was normal. PMN phagocytic function in vivo was determined by the clearance of viable Escherichia coli from subcutaneously implanted sponges and no significant difference between control and uremic groups was found. These studies have further defined the effect of uremia on immune mechanisms and support our contention that uremia per se is not a major factor contributing to the compromised immune status in this host.

Hepatic reticuloendothelial function in the sub-totally nephrectomized rat model of chronic uremia

The chronic uremic condition was induced in male Wistar rats by long term maintenance of the animals following sequential sub-total and contralateral nephrectomies. Hepatic reticuloendothelial (RES) activity was estimated by non-invasive measurement of blood clearance rates and hepatic uptake of 99Tcm sulfur colloid administered intravenously. The blood half-time, and the blood clearance rate constants for normals and chronic uremics were 78 +/- 10 s and 49.5 +/- 5 s, and 7.51 +/- 1.04 x 10(-3) s-1 and 10.81 +/- 1.17 x 10(-3) s-1 respectively. The normal hepatic uptake rate constant was 9.03 +/- 1.25 x 10(-3) s-1, compared with a uremic uptake rate constant of 14.34 +/- 1.51 s-1. Measurement of total liver radioactivity upon termination, 15 min after injection, showed significantly increased total uptake in uremia, whereas no change in spleen radioactivity was observed. The clinical implications of these data are discussed.

The effects of acute and chronic uremia in rats on their hepatic microsomal enzyme activity

The activity of the hepatic microsomal enzymes hexabarbital oxidase, aminopyrine demethylase, and p-nitrobenzoic acid reductase were determined in the chronically uremic rats, acutely uremic rats and controls. Plasma corticoid levels (corticosterone) were also measured in all groups. A significant reduction in the hepatic microsomal enzyme activity as compared to controls was observed in both groups, with the chronic group showing slightly greater reduction. Furthermore, while plasma corticoid levels were significantly elevated in both groups, the acute uremic group had plasma corticoid levels which were almost twice the levels found in the chronically uremic animals. The significance of these observations are discussed.