Role of caspases on cell death, inflammation, and cell cycle in glycerol-induced acute renal failure.

Caspases are the main executioners of apoptosis as well as interleukin (IL)-1beta and IL-18 conversion to active forms. They are activated after acute kidney injuries. In this study, we evaluated the importance of the caspase family in the pathogenesis and recovery of glycerol-induced acute renal failure in rats (Gly-ARF). Rats were treated with pan-caspase or selective caspase 1 and 3 inhibitors at the moment we injected glycerol. Renal function, renal histology (HE), transferase-mediated deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling staining for apoptosis, leukocytes infiltration (immunohistochemistry), renal expression of IL-1beta and IL-18 (immunohistochemistry and Western blot), tubular regeneration (5-bromo-2'-deoxyuridine (BrdU) incorporation), and P27(Kip) expression (Western blot) were evaluated at appropriate times. All inhibitors reduced the renal function impairment. Pan-caspase and caspase-3 inhibitors reduced cellular death (necrosis and apoptosis) 24 h after Gly-ARF. All caspases inhibitors reduced macrophages infiltration. The expression of total IL-1beta was enhanced in Gly-ARF, but the active IL-1beta and IL-18 forms were abolished in pan-caspase treated rats. Caspase-1 inhibitor attenuated Gly-ARF but not tubular injury suggesting glomerular hemodynamic improvement. There was striking regenerative response 48 h after Gly-ARF characterized by enhanced BrdU incorporation and reduced expression of p27(Kip). This response was not blunted by caspases inhibition. Our findings demonstrate that caspases participate in important pathogenic mechanisms in Gly-ARF such as inflammation, apoptosis, vasoconstriction, and tubular necrosis. The early inhibition of caspases attenuates these mechanisms and reduces the renal function impairment in Gly-ARF.

Accelerated recovery of glycerol-induced acute renal failure in rats with previous partial hepatectomy.

Several studies have reported a favorable effect following the administration of growth factors during the course of acute renal failure. To evaluate the effect of an increased endogenous production of growth factors, rats underwent 70% hepatectomy before glycerol-induced acute renal failure. The renal function was then monitored 12 and 48 h after glycerol injection in conscious rats. Twelve hours after the induction of acute renal failure, a reduction in creatinine clearance and sodium reabsorption was seen in both prehepatectomized and sham-hepatectomized rats. At 48 h, there was total recovery of glomerular filtration and tubular function in the prehepatectomized rats, whereas the sham-hepatectomized rats still had reduced glomerular filtration and sodium reabsorption. In rats treated with dexamethasone before hepatectomy and studied 48 h after the induction of acute renal failure, the protective action on renal function seen in prehepatectomized rats was totally blocked. A semiquantitative histological analysis done 48 h after the induction of acute renal failure demonstrated a fourfold increase in the number of necrotic tubules in both sham-hepatectomized and dexamethasone-treated rats as compared with hepatectomized rats. It is concluded that partial hepatectomy, a maneuver used to increase the endogenous synthesis of growth factors, accelerates recovery of renal function following glycerol-induced acute renal failure.

Prophylaxis of acute renal failure in patients with rhabdomyolysis.

Patients that develop rhabdomyolysis of different causes are at high risk of acute renal failure. Efforts to minimize this risk include volume repletion, treatment with mannitol, and urinary alkalinization as soon as possible after muscle injury. This is a retrospective analysis (from January 1, 1992, to December 31, 1995) of therapeutic response to prophylactic treatment in patients with rhabdomyolysis admitted to an intensive care unit (ICU). The diagnosis of rhabdomyolysis was based on creatinine kinase (CK) level (> 500 Ui/L) and the criteria for prophylaxis were: time elapsed between muscle injury to ICU admission < 48 h and serum creatinine < 3 mg/dL. Fifteen patients were treated with the association of saline, mannitol, and sodium bicarbonate (S + M + B group) and 9 patients received only saline (S group). Serum creatinine at admission was similar in both groups: 1.6 +/- 0.6 mg/dL in the S + M + B group and 1.5 +/- 0.6 mg/dL in the S group (p > 0.05). Maximum serum CK measured was 3351 +/- 1693 IU/L in the S + M + B group and 1747 +/- 2345 IU/L in the S group (p < 0.05). However the measurement of CK was earlier in S + M + B patients (1.7 vs 2.7 days after rhabdomyolysis). APACHE II scores were 16.9 +/- 7.4 and 13.4 +/- 4.9 in the S + M + MB and S groups, respectively (p > 0.05). Despite the treatment protocol the serum levels of creatinine had similar behavior and reached normal levels in all patients in 2 or 3 days. The saline infusion during the first 60 h on the ICU was 206 mL/h in the S group and 204 mL/h in S + M + B (p > 0.05). Mannitol dose was 56 g/day, and bicarbonate 225 mEq/day during 4.7 days. Our data show that progression to established renal failure can be totally avoided with prophylactic treatment, and that once appropriate saline expansion is provided, the association of mannitol and bicarbonate seems to be unnecessary.

Acute renal failure due to rhabdomyolysis in diabetic patients.

We report a 32-year-old Black man, admitted to the ICU with coma and severe metabolic disturbances due to diabetic ketoacidosis. During the admission, rhabdomyolysis and acute renal failure (ARF) were diagnosed. After metabolic control and gradual decrease of creatine kinase levels, he presented a progressive improvement of renal function. We emphasize nontraumatic rhabdomyolysis as a poorly recognized pathogenetic factor for ARF in diabetic ketoacidosis and suggest that a better understanding of its mechanisms and an early application of protective measures is necessary.

Acute ureteral obstruction and glomerulotubular function in rats.

Urinary tract obstruction is a common cause of acute renal failure (ARF). During unilateral ureteral obstruction (UUO) arteriolar vasoconstriction, increase in tubular pressure, and ultrafiltrate retrodiffusion occur. We studied renal function of rats with surgical UUO for 24 hr. After this period of UUO, the contralateral kidney was removed and the right ureter was deobstructed. The control uninephrectomized group consisted of normal rats submitted to left uninephrectomy (UNx). Functional studies were performed 12 and 24 hr, and 7 days after deobstruction and UNx. We measured creatinine clearance, and fractional excretion of sodium and lithium. Using conventional formulas we calculated fractional proximal and distal sodium reabsorption. Initially we observed a reduction in glomerular filtration rate (GFR) after deobstruction (12 and 24 hr). However, after 7 days, the GFR was significantly higher in deobstructed rats than in controls (340.3 +/- 18.3 vs. 286.4 +/- 9.3 microL/min/100 g, p < 0.01). The dry kidney weight was also increased in these rats. The fractional sodium excretion was increased in deobstructed rats, mainly in early studies (12 and 24 hr). Whereas fractional proximal reabsorption was reduced in both groups, the fractional distal reabsorption was significantly decreased in the deobstructed group compared to UNX controls (93.9 +/- 0.9 vs. 98.9 +/- 0.1% after 24 hr, p < 0.01). Our data showed that UUO influenced both glomerular and tubular functions. A salient finding was the overcorrection of GFR 7 days after deobstruction. The renal release of hormones and growth factors could mediate these alterations in renal function through their vascular, tubular, and proliferative actions.

Effects of nifedipine and platelet activating factor antagonist (BN 52021) in glycerol-induced acute renal failure in rats.

We studied the actions of nifedipine and the platelet activating factor (PAF) antagonist BN 52021 on renal and tubular function in glycerol-induced acute renal failure (Gly-ARF). The tubular handling of sodium was evaluated through the lithium clearance method in awake rats in metabolic cages. The sequential analysis of tubular function 3, 6, 12, and 24 h after Gly-ARF showed a sharp decrease in fractional proximal Na reabsorption (FPRNa)--control 74.1 +/- 12.5%, 3 h: 79.5 +/- 6.0%; 6 h: 41.8 +/- 15.9%; 12 h: 22.9 +/- 17.9%; and 24 h: 31.1 +/- 16.2% (p < 0.001) while fractional distal Na reabsorption (FDRNa) did not change during the study. The effect of nifedipine (20 mg/kg p.o.) and BN 52021 (1 mg/kg i.p.) were evaluated 24 h after the induction of Gly-ARF. Both drugs attenuated the reduction in creatinine clearance (control 431.8 +/- 108.2, glycerol 96.7 +/- 43.8, glycerol plus nifedipine 264.9 +/- 103.5, and glycerol plus BN 52021 188.9 +/- 69.8 microL/min/100 g, p < 0.001). However, only nifedipine could keep FPRNa higher than untreated rats (58.3 +/- 13.2 vs. 31.1 +/- 16.2%, p < 0.05) and reduced the tubular necrosis on histologic semiquantitative analysis. Our data showed that nifedipine and BN 52021 could protect against filtration failure in Gly-ARF but that only nifedipine reduced the proximal tubular lesion.

Nonamyloidotic fibrillary glomerulopathy. Report of a case and review of the literature.

A 29-year-old man had oedema, proteinuria in nephrotic range, haematuria and cardiac arrhythmia (second grade atrioventricular block). The pathologic findings of kidney biopsy showed in light microscopy diffuse mesangial matrix increase with mild mesangial proliferation and variable thickening of the glomerular capillary walls. IgG, c3 and c1q were intensely fluorescent and exhibited a diffuse granular pattern in mesangial areas and along the capillary walls. Both kappa and lambda chains were weakly positive in the same pattern. Ultrastructurally, microfibrils of about 20 nm in width were seen to be deposited in mesangial areas and along the glomerular basement membranes. Congo red stain and metachromasia were negative. Neither cryoglobulinaemia nor paraproteinaemia including light chains were found. The aetiology of nonamyloidotic fibrillary glomerulopathy is unknown and no clear-cut clinical or pathologic pattern has emerged. It may represent more than one disease process with a common morphologic expression.

Acute hemodynamic action of captopril in congestive heart failure: contrasts between refractory and untreated patients.

To compare the hemodynamic mode of action of captopril in patients with Congestive Heart Failure (CHF) with high- or low-plasma renin activity, we studied the systemic and renal hemodynamic changes induced by this drug in patients with refractory CHF (Group I) or untreated CHF (Group II). Plasma Renin Activity (PRA) was 7.46 +/- 3.7 ng/ml/hr in Group I and 1.15 +/- 0.45 ng/ml/hr in Group II. After the administration of captopril, these values increased to 14.35 +/- 6.19 and to 1.99 +/- 0.76 ng/ml/hr respectively (p less than 0.05). We observed that patients of Group I responded with increases in cardiac index and stroke volume and diminutions in total peripheral resistance, but Group II did not show any significant change in these variables. In contrast to this difference in responses between the refractory and untreated patients, both groups showed similar decreases in pulmonary artery and wedge pressures. Both groups also showed similar increases in plasma volume and effective renal plasma flow, and decreases in renal vascular resistance. These results show that captopril has predominantly venodilator effects in patients with CHF with low PRA levels, and it acts as a mixed vasodilator in patients refractory to conventional therapy, receiving high doses of diuretics, and in whom PRA is elevated. Our results also suggest that the venodilator action of captopril is not mediated by the Renin-Angiotensin System.

Hemodynamic mechanism of blood pressure response to captopril in human malignant hypertension.

The hemodynamic mechanism of blood pressure response to angiotensin blockade is well established in "benign" but not in human malignant hypertension. We studied the changes in mean arterial pressure (MAP), cardiac index (CI), pulmonary wedge pressure (PWP), and in plasma volume (PV) induced by a single oral dose of captopril (150 mg) in 11 patients with malignant hypertension. Two hours after captopril, MAP fell from 178.5 +/- 5.8 to 151.8 +/- 7.8 mm Hg (p less than 0.001) (means +/- SEM) due to a fall in total peripheral resistance (TPR) (from 54.8 +/- 6.8 to 46.4 +/- 1.6 arbitrary units, p less than 0.001). However, there was a simultaneous increase in CI (from 3.29 +/- 0.13 to 3.70 +/- 0.15 liter/min/m2, p less than 0.001), and a decrease in PWP (from 15.3 +/- 3.5 to 11.0 +/- 2.5 mm Hg, p less than 0.001), while PV remained unchanged (from 4.02 +/- 0.26 to 4.12 +/- 0.12 liters, n.s.). Our data show that, in human malignant hypertension, blood pressure response to captopril is due to a decrease in TPR, but in contrast to benign hypertension, there is also a simultaneous increase in CI. Our results suggest that, in malignant hypertension, potentially high CI levels are artificially normalized by the increased TPR and may be fully disclosed by vasodilation.