Pyelonephritic Animals Research Articles

Increased nephrotoxicity of gentamicin in pyelonephritic rats

Multiple factors may increase the nephrotoxic potential of aminoglycosides. We studied gentamicin susceptibility of kidneys infected with E. coli. Several parameters of renal function, histological changes on light and electron microscopy, and drug levels in renal parenchyma were compared in pyelonephritic and normal rats treated with low doses (10 mg/kg/Q8 hr for 3 days), or high doses (60 mg/kg/day for 14 days), of gentamicin. A significant increase (P less than 0.01) in beta-galactosidase and protein excreted in urine over a period of 17 days associated with severe changes in diuresis and osmolality was noted in the infected treated rats (low doses) compared with normal, treated, infected or control animals. Histological modifications compatible with gentamicin nephrotoxicity were more persistent in the infected treated animals. A significant decrease in 14C inulin (P less than 0.01) and 3H-PAH clearance and secretion (P less than 0.02) was observed in the infected treated rats receiving high doses of antibiotics. Cellular necrosis and tubular desquamation also were more severe in this group. Gentamicin levels in the cortex and medulla of infected animals were significantly higher than in the normals (P less than 0.01) and might have been responsible for the increased toxicity noted in the pyelonephritic animals. Infected kidneys appeared to be more susceptible to the nephrotoxic potential of gentamicin.

Auto-antibody to kidney tubular cells during retrograde chronic pyelonephritis in rats.

Retrograde pyelonephritis was induced in inbred Fischer rat kidneys with Proteus mirabilis (1 X 10(8) organisms/ml). Sera from pyelonephritic animals sacrificed at 4 and 6 weeks contained cytotoxic antibodies to cultured syngeneic 51Cr-labeled kidney tubular cells (p less than 0.02 and p less than 0.05, respectively) which could be absorbed with plasma membranes. Immune sera from 4- and 6-week pyelonephritic animals also displayed a granular fluorescent pattern along the surface of cultured kidney tubular cells. Quick-frozen syngeneic rat kidney sections stained positively with fluorescent antibody on the intraluminal side of kidney tubular cells. The results suggest that during chronic phases of pyelonephritis, auto-antibodies to kidney tubular cells are induced.

Infection-induced immunosuppression in pyelonephritis: Characteristics of the suppressor cell(s)

Infection-induced suppressor cells may be associated with a depression of cell-mediated immune (CMI) mechanisms in pyelonephritis. In the present study, cell viability and cell to cell contact were established as prerequisites for immunosuppression and the role of mononuclear phagocytic cells and polymorphonuclear leukocytes, as immunoregulatory cells affecting CMI, was also examined. Fractionation of spleen cell suspensions was carried out using carbonyl iron, nylon wool, glass beads, and sephadex. These procedures restored mitogenic responsiveness to splenic lymphocytes from pyelonephritic animals, and it was possible to isolate cells with accessory and suppressor activity from nylon wool columns. Elutable cells (that is, cells which adhere to the column but could be recovered by the addition of EDTA) were characteristically accessory cells and increased the mitogenic responsiveness of normal lymphocytes. Adherent splenocytes which suppress mitogenic responses were isolated from pyelonephritic animals. Additionally, neutrophils, at concentrations readily demonstrable in lesions, depressed CMI responses in vitro. With this information available it should now be possible to carry out a detailed analysis of the cellular mechanism by which CMI in renal infection is depressed.

Intrarenal concentrations of ampicillin in acute pyelonephritis.

The intracortical, medullary, and papillary distribution of ampicillin was studied in normal and pyelonephritic rats. At 4 days after induction of pyelonephritis, the animals were given a single injection of 100 mg of ampicillin per kg or were treated for 1 week with two daily doses of 100 mg/kg. Major differences in the intrarenal distribution of ampicillin were noted between normal and pyelonephritic animals. At 2 hours after injection, the concentrations of ampicillin in all parts of the infected kidneys were significantly lower (P less than 0.05) than in normal kidneys. The area under the curve (micrograms.minute per milliliter) over a 4-h period after single injection was much lower in the medulla (6.3 +/- 0.9) and papilla (29.6 +/- 4.2) of infected kidneys than in the medulla (11.2 +/- 1.6) and papilla (44 +/- 10.1) of noninfected kidneys. Whereas the ratio of concentration in tissue to concentration in serum ranged to 11.1 in the papilla of normal animals, this ratio was reduced to 2.4 in the presence of pyelonephritis. The diminution of the concentration gradient was also striking in the urine, where there was a reduction of more than threefold in pyelonephritic animals. One week of therapy resulted in a noticeable reduction of the inflammatory process associated with a return to near-normal intrarenal distribution of ampicillin. In normal rats treated with multiple doses, there were decreases of the antibiotic concentrations in serum and kidneys and in the area under the curve for these tissues.

Suppressor cell regulation of cell-mediated immune responses in renal infection in vitro modulation of suppressor cell activity.

Infection-induced anergy is a frequent complication of bacterial, viral, and parsitic infection. A marked suppression of the thymus-derived (T) lymphocyte response to concanavalin A has been demonstrated in vitro during renal infection and the mechanisms by which suppression occurs have been investigated. In particular we have considered the possibility that suppression might result from the inhibitory effect of prostaglandins, secreted by activated macrophages with immunoregulatory potential. The experiments have shown that the T-lymphocyte effector status in experimentally-induced renal infection is determined by two suppressor cells, one infection-induced and the other naturally occurring. The inability to respond to mitogenic stimulation was reversible and restoration of immune responsiveness to splenic lymphocytes from infected animals could be achieved in two stepwise manipulations; differential centrifugation removed the infection-induced suppressor cells, and the suppressor activity of the naturally occurring suppressor cells could then be inhibited by indomethacin. Thus the two suppressor cells were distinguishable on the basis of their physical characteristics and their response to indomethacin. The dominant factor determining the immune responsiveness of splenic lymphocytes from the pyelonephritic animals was, however, the infection-induced suppressor cell. This cell has been characterized as a sedimentable cell (30 g) with suppressor activity demonstrable in co-culture experiments. Plastic-adherent cells from the sedimentable fraction of pyelonephritic animals' splenic cells were shown to have suppressor activity that was not inhibited by indomethacin. The infection-induced and naturally occurring suppressor cells can be viewed as prototypes for the equivalent cells in man and may be useful models for studying the role of these cells as determinants in the pathogenesis of infectious disease.

Modification by Suppressor Cells and Serum Factors of the Cell-Mediated Immune Response in Experimental Pyelonephritis

A marked suppression of the thymusderived (T)-lymphocyte response to concanavalin A has been demonstrated in vitro during renal infection. Suppression of the T-lymphocyte response in vitro was seen as early as 2 h after the induction of renal infection, but maximum suppression was found 24-72 h later. A population of suppressor cells in the splenic lymphocyte population, generated during the host's response to infection, contributed to the depressed lymphocyte response. Removal of suppressor cells restored the mitogenic responsiveness of the remaining splenic lymphocytes. Conversely, in co-culture experiments, a suppressor cell present in the splenic lymphocyte population of pyelonephritic animals was shown to be capable of suppressing the mitogenic responsiveness of normal splenic lymphocytes. Significantly reduced host vs. graft responses by the pyelonephritic animals confirmed, in vivo, the depression of cell-mediated immune mechanisms. An additional suppressive factor was found in the serum of pyelonephritic animals which depressed in vitro the mitogenic responsiveness of splenic lymphocytes from normal animals. Support for the suppressive role of this serum factor was found when splenic lymphocytes from pyelonephritic animals were tested in vivo in the absence of homolgous serum (graft vs. host). Under these conditions, the lymphocytes showed an enhanced reaction compared with lymphocytes from normal animals. The presence of a suppressor cell population and a serum factor, both capable of depressing cell-mediated mechanisms, may be major factors contributing to the establishment of infection in the kidney.

A study of the intrarenal recycling of urea in the rat with chronic experimental pyelonephritis.

The concentrating ability of the kidney was studied by clearance and micropuncture techniques and tissue slice analyses in normal rats with two intact kidneys (intact controls), normal rats with a solitary kidney (uninephrectomized controls), and uremic rats with a single pyelonephritic kidney. Urinary osmolality after water deprivation for 24 h and administration of antidiuretic hormone was 2,501+/-217 and 2,874+/-392 mosmol/kg H2O in intact and uninephrectomized control rats, respectively, and 929+/-130 mosmol/kg H2O in pyelonephritic rats (P less than 0.001 compared to each control group). Fractional water reabsorption and concentrating ability were significantly decreased in the pyelonephritic group, and, to achieve an equivalent fractional excretion of urea, a greater fractional excretion of water was required in the pyelonephritic rats than in the control rats. Whole animal glomerular filtration rate was 1.57+/-0.19 ml/min and 1.39+/-0.18 ml/min in intact and in uninephrectomized controls, respectively, and 0.30+/-0.07 ml/min in pyelonephritic rats (P less than 0.001 compared to each control group). Single nephron glomerular filtration rate was 35.6+/-3.8 nl/min in intact control rats and was significantly increased (P less than 0.05) in both uninephrectomized (88.0+/-10.8 nl/min) and pyelonephritic rats (71.5+/-14.4 nl/min). In all groups fractional water delivery and fractional sodium delivery were closely comparable at the end of the proximal convoluted tubule and at the beginning of the distal convoluted tubule. In contrast, fractional urea delivery out of the proximal tubule was greater in the intact control group (73+/-8%) than in either the uninephrectomized (52+/-2%) or the pyelonephritic group (53+/-3%) (P less than 0.005). Fractional urea delivery at the early part of the distal tubule increased significantly to 137+/-11% and 93+/-6% of the filtered load in intact control and uninephrectomized control rats, respectively (P less than 0.001 compared to the late proximal values of each group), but failed to increase significantly in pyelonephritic rats (65+/-13%), indicating interruption of the normal recycling of urea in the latter group. Analysis of tissue slices demonstrated a rising corticopapillary gradient for total tissue water solute concentration as well as for tissue water urea concentration in both groups of control rats. In contrast, the pyelonephritic animals exhibited no similar gradients from cortex to papilla. These data indicate that the pyelonephritic kidney fails to recycle urea and accumulate interstitial solute. The latter must inevitably lead to a concentrating defect.

Experimental pyelonephritis: The effect of chronic active pyelonephritis on renal function

In these experiments, renal function in chronic active pyelonephritis was investigated and the effect of antibiotic treatment and elimination of infection on the gross pathology, histopathology and renal function in animals with chronic pyelonephritis was determined. A severe loss of urine concentrating capacity was demonstrable when the maximum urinary osmolality of a group of animals with pyelonephritis was compared with control animals. Concentrating capacity decreased sharply over the first month but further loss over an eight-month period was minimal. A compensatory increase in the glomerular filtration rate (GFR) in the control, nonchallenged, group occurred after nephrectomy but no comparable compensation in the infected group was found. Antibiotic therapy had a marked effect on the urinary concentrating capacity and the defect in concentrating ability was significantly less in the treated animals during the first 30 days after challenge. Infection again prevented a compensatory increase in the GFR of pyelonephritic animals which was not reversed by antibiotic therapy. Blood urea concentrations in treated and nontreated animals were not significantly different nor did the eradication of infection affect the gross pathologic and histopathologic changes found at autopsy.

Renal Handling of β2-Microglobulin in Experimental Renal Disease

Renal extraction and urinary excretion of 125I-labelled beta2-microglobulin was studied in rats. The effect of ischaemic renal injury, experimental pyelonephritis, and unilateral nephrectomy was investigated. The tubular secretion of o-iodohippurate (OIH) was measured for comparison. The urinary excretion was calculated as the ratio between the clearance of protein and the glomerular filtration rate. The glomerular filtration rate was estimated as clearance of polyethylene glycol (PEG 1000). The renal arteriovenous concentration difference was lower for beta2-microglobulin than for PEG 1000 IN ALL THE EXperimental groups. In unilateral renal disease the beta2-microglobulin excretion of the intact kidneys was similar to that of the diseased kidneys. A significant differences was noted only after ischaemic renal injury. The same was found for OIH. After removal of the intact kidneys the excretion of beta2-microglobulin increased about 10-fold in pyelonephritic animals and 2- to 30-fold in animals with ischaemic renal injury. One hour after unilateral nephrectomy in normal animals the ratio increased about 50 per cent. The tubular secretion of OIH did not change noticeably. It is concluded that the glomerular filtration is a main step in the intrarenal catabolism of beta2-microglobin and that its urinary excretion is considerably influenced by a reduction in the functioning kidney mass.

The diagnostic value of enzymuria, cell excretion, and proteinuria in experimental renal diseases.

Enzymuria, urinary cell excretion and proteinuria were simultaneously determined in renal diseases of female Wistar rats in order to investigate the diagnostic value of urinary enzymes. Investigations were carried out on rats with E. coli-pyelonephritis facilitated by oestradiolundecylate, aminonucleoside nephrosis, aminoglycoside induced renal lesions and pyelonephritic animals treated with therapeutic and toxic doses of tobramycin. --From the results of these studies it was concluded that the main diagnostic value of urinary enzymes is detection of drug induced tubular lesions in individuals with preexisting renal diseases.

Local immune response in experimental pyelonephritis

Experiments using an in vitro method of assessing protein synthesis by (14)C amino acid incorporation were designed to determine whether pyelonephritic kidneys were capable of local antibody production. Unilateral pyelonephritis was produced in rabbits by intravenous injection of E. coli 0-75 while one ureter was transiently occluded. The capability of protein and immunoglobulin synthesis by pyelonephritic kidneys, contralateral kidneys, normal kidneys, and spleens from normal and pyelonephritic animals was measured. Enhanced protein and immunoglobulin syntheses by pyelonephritic kidneys were first detected by the 11th day after infection and persisted through day 120. In individual experiments the pyelonephritic kidney produced 6-170 times more soluble protein than did the contralateral, uninfected kidney. In seven experiments, IgG comprised a mean of 72% of the total protein synthesized by the pyelonephritic kidney, compared with a mean of 19% in the contralateral kidney. IgA accounted for 10 and 9%, respectively. In these experiments 0.6-17% of the synthesized IgG was precipitable by somatic antigen of the E. coli 0-75. The capability of the pyelonephritic kidney to synthesize soluble protein was quantitatively similar to that of spleens from infected animals. The proportion of synthesized protein which was immunoglobulin G, however, was greater in the pyelonephritic kidney than in the spleen. Furthermore, specific antibody synthesis by the pyelonephritic kidney persisted longer than did synthesis by the spleen of the same animal. These studies provide evidence that in experimental pyelonephritis a significant local immune response occurs which is represented primarily by the production of IgG. Local immunoglobulin formation and specific antibody synthesis may be important factors in determining patterns of host resistance.

Functional Studies in Experimental Pyelonephritis

The ability to excrete an acid load was compared in normal and pyelonephritic rats and correlated with the histochemically-determined level of the following enzymes: Glutaminase I, glutamic dehydrogenase, carbonic anhydrase, NADH diaphorase, NADPH diaphorase, and ATPase. Ammonia excretion at all levels of acid intake up to 10 mEq/day was equivalent in both groups of animals. In the normal animals adaptive increases in activity of glutaminase I, glutamic dehydrogenase, NADH diaphorase and NADPH diaphorase were seen after acid loading. The pyelonephritic animals differed primarily in that diminished activity of glutaminase I was demonstrable on both neutral and acid-ash diets. Tubules caught within scars showed a significant reduction in activity of all enzymes. The results suggest that an intrinsic disease process (i.e., pyelonephritis) may be capable of decreasing the ability of certain enzymes to adapt to physiologic stimuli. In the present study model, however, the diminution in activity of glutaminase I appeared insufficient to limit ammonia production.

Individual nephron function in experimental bilateral pyelonephritis. II. Distal tubular sodium and water reabsorption and the concentrating defect.

Abstract The renal concentrating defect in rats with nonobstructive bilateral pyelonephritis was studied by combined clearance and micropuncture methods. Control groups consisted of normal rats and those in which approximately 65 to 70 per cent of renal mass had been ablated by bilateral subtotal nephrectomy. The residual functioning renal mass and solute load per nephron were estimated to be of about the same order of magnitude in the pyelonephritic and partially nephrectomized animals. It was found, however, that both U max and t c h 2 o were diminished to a greater extent in the rats with intrinsic renal disease. Measurements of osmolality, sodium, and inulin concentrations in the distal tubular fluid of surviving cortical nephrons failed to reveal any specific defect in sodium transport by the thick ascending limb of Henle's loop, or any change in the permeability characteristics which could account for the severity of the concentrating defect in the pyelonephritic animals. The data suggest, rather, that at comparable rates of total solute excretion in the urine, individual surviving loops of Henle in the pyelonephritic rats were actually transporting more sodium into the medullary interstitium than were the loops in the normal controls. The concentrating defect in the pyelonephritic animals thus could not be accounted for by the reduction in renal mass, by the adaptational increases in glomerular filtration rate per surviving nephron, or by any detectable defect in salt or water transfer in individual cortical nephrons. The observations localize the disturbance to the renal medulla. It is suggested that disruption of the architecture of the renal medulla may be an important factor contributing to the concentrating defect.