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To gain further insights into the molecular mechanisms involved in acute renal failure, we have isolated a new gene from rat and human, named KSP32 (kidney-specific protein with a molecular mass of 32 kDa). KSP32 encodes a novel gene that shows little homology to other mammalian proteins. It, however, shares extensive homology with several proteins found in the nematode Caenorhabditis elegans and plants. The expression of KSP32 mRNA is highly restricted to kidney. In situ hybidization analysis revealed that the expression of KSP32 mRNA was prominent in the boundary of kidney cortex and outer medulla, exhibiting a raylike formation extending from the medulla into the cortex. Finally, KSP32 mRNA was dramatically downregulated in rat following induction of acute ischemic renal failure. Rapid loss of KSP32 mRNA expression was observed beginning at approximately 5 h following renal injury and mRNA levels remained depressed for at least 96 h. Both KSP32 mRNA levels as well as renal function recovered 14 days after injury. Administration of an endothelin receptor antagonist (SB-209670), known to restore renal function, significantly increased KSP32 expression.

The purpose of this study was to examine the effects of the peptidoleukotriene receptor antagonist, SK&F 104353, on the responses to endotoxin in conscious male Sprague-Dawley rats. Administration of Salmonella enteritidis endotoxin (30 mg/kg i.v.; LD90) resulted in a decrease in the number of circulating platelets, leukopenia, an increase in hematocrit, and 0% survival at 24 hr. Pretreatment with SK&F 104353 (1 mg/kg, i.v. bolus followed by 3 mg/kg/hr, i.v. infusion for 6 hr) 5 min before injection of endotoxin produced steady state plasma drug levels of 1.6 micrograms/ml in naive animals and levels of approximately 3.4 micrograms/ml in endotoxemic animals (P less than 0.05). SK&F 104353 significantly attenuated the endotoxin-induced thrombocytopenia (P less than 0.05) but had no effect on either the endotoxin-induced early leukopenia or late leukocytosis. Additionally, SK&F 104353 significantly reduced the endotoxin-induced hemoconcentration (P less than 0.05) and improved survival to 30% at 48 hr (P less than 0.05). A higher dose of SK&F 104353 (2 mg/kg, i.v. bolus followed by 10 mg/kg/hr, i.v. infusion for 6 hr) did not produce any further benefit. These data indicate clearly the pathophysiologic role of peptidoleukotrienes in endotoxemia and suggest SK&F 104353 could be useful for ameliorating some of the deleterious sequelae associated with this condition.

Endotoxemia is associated with increases in a number of humoral mediators including vasopressin, thromboxane and leukotrienes (LT), all of which may participate in the pathophysiologic responses to endotoxemia. Previous studies from our laboratory demonstrated that endotoxin-induced hemoconcentration was attenuated with a peptidoleukotriene receptor antagonist, SK & F 104353. The purpose of this study was to investigate further the mechanism of endotoxin-induced hemoconcentration. Injection of LTD4 (51 nmol/kg, i.v.) produced an increase in the hematocrit of conscious male Sprague-Dawley rats: administration of SK & F 104353 (2 mg/kg, i.v. + 10 mg/kg/h, i.v. infusion) blocked completely this response to exogenous LTD4. Injection of Salmonella enteritidis endotoxin (30 mg/kg, i.v.) increased the hematocrit from 41 +/- 1 vol% to 55 +/- 1 vol%. Following pretreatment with SK & F 104353 (2 mg/kg, i.v. + 10 mg/kg/h, i.v.), the hemoconcentration was attenuated to 46 +/- 1 vol% (p less than 0.01). Simultaneous determination of plasma drug concentrations over a range of doses indicated that inhibition of the hemoconcentration produced by SK & F 104353 was concentration-dependent (IC30 = 0.5 microgram/ml). The IC30 for the stereoisomer, SK & F 104373, was 50 micrograms/ml. The 5-lipoxygenase/cyclooxygenase inhibitors, SK & F 86002 and BW 775C, also attenuated the endotoxin-induced increase in hematocrit, whereas indomethacin, heparin, daltroban, or the selective V1 vasopressin receptor antagonist [d(CH2)5Tyr(Me)]AVP did not significantly affect the endotoxin-induced hemoconcentration. The endotoxin-induced hemoconcentration was inhibited in a concentration-dependent, stereoselective manner with a peptidoleukotriene receptor antagonist, and by 5-lipoxygenase inhibitors, indicating that this response is mediated by peptidoleukotrienes.

The following studies were designed to evaluate the efficacy of a potent and selective AVP V1 receptor antagonist ([1-beta-mercapto-beta, beta-cyçlopentamethyleneproprionic acid, 2-(O-methyl)tyrosine-8-arginine vasopressin]; AVPRA) in limiting the sequelae of endotoxemia. At 0.5 and 1.0 hr after intravenous injection of 30 mg/kg S. enteritis endotoxin (LPS) to male Sprague-Dawley rats, AVP plasma concentrations were increased to 171 +/- 20 and 100 +/- 24 pg/ml, respectively, and were significantly greater than the vehicle control values of 1 pg/ml. Injection of LPS was accompanied by the following: a decreased survival rate (20%) with a mean survival time of 21.6 +/- 6 hr (n = 10), an increased heart rate (+ 84 +/- 22 bpm), a reduced circulating platelet count (23% of initial), and an acute hemoconcentration that was maximal at 30 min after injection of LPS. In a separate group of conscious rats, it was determined that AVPRA (1-100 mg/kg/hr) produced a dose-dependent, parallel and rightward shift in the AVP vasopressor dose-response curve: the highest dose of AVPRA (i.e., 100 micrograms/kg/hr) produced approximately a 1,000-fold shift in the AVP dose-response curve. Administration of AVPRA (1-100 micrograms/kg/hr) beginning 15 min prior to the injection of LPS and continuing for 6 hr did not significantly limit any of the sequelae produced by endotoxemia. These results suggest that, in this model, acute administration of a potent V1 AVP antagonist (AVPRA) is not sufficient to prevent the cardiovascular sequelae and mortality associated with endotoxemia.

The potential role of coagulation defects as a pathologic mediator in septic shock is well documented, especially as it relates to increased thromboxane formation, thrombocytopenia, and disseminated intravascular coagulation. The present study was designed to determine the effect of the thrombolytic agent streptokinase on the sequelae of endotoxemia in the rat. Conscious male Sprague-Dawley rats were given a bolus intravenous dose of Salmonella enteritidis endotoxin (20 mg/kg; LD90 dose) 5 min after the intravenous administration of streptokinase (10,000 U/kg bolus + 1,000 U/kg/hr infusion), or heparin (100 U/kg bolus + 30 U/kg/hr infusion). The effects of streptokinase or heparin on blood clotting were determined by measuring ex vivo clot formation 1 hr after the administration of endotoxin. In naive and endotoxemic animals, both agents significantly reduced clot formation (P less than 0.05). In endotoxemic animals, streptokinase or heparin improved survival to 70%, compared to 8% survival in the endotoxin + vehicle group (P less than 0.05). The improvement in survival with streptokinase was dose-dependent. Neither streptokinase nor heparin prevented the thrombocytopenia or hemoconcentration which developed in endotoxemic animals. These results demonstrate the potential utility of streptokinase for improving survival in endotoxemia and further confirm the deleterious contribution of coagulation disorders in endotoxic mortality.

The purpose of this study was to examine the effects of the thromboxane receptor antagonist, BM 13.505, on the responses to endotoxemia in the conscious rat. The pharmacodynamics of BM 13.505 (30 mg/kg, i.v.) were first determined by pretreating male Sprague-Dawley rats 5 min, 24 h or 48 h prior to an LD90 dose of the thromboxane mimetic U 46619. Administration of a single dose of BM 13.505 5 min or 24 h prior to the challenge with U 46619 protected completely against sudden death (100% survival, p less than 0.01), while injection of BM 13.505 48 h prior to the U 46619 challenge did not protect against death. In a separate group of conscious rats, endotoxemia (30 mg/kg i.v. Salmonella enteritidis endotoxin) produced a decrease in the number of circulating platelets to 45 +/- 4% and 20 +/- 4% of the initial value at 1 and 6 h, respectively. The number of circulating white blood cells was reduced to 21 +/- 4% of the initial value at 1 h and returned to 68 +/- 9% of the initial value at 6 h. Survival following endotoxin administration was 44% at 48 h. In endotoxemic animals pretreated with BM 13.505 (30 mg/kg, i.v.), the endotoxin-induced thrombocytopenia was significantly attenuated (p less than 0.05), but there was no effect on either the endotoxin-induced early leukopenia or late leukocytosis. Survival in the BM 13.505-treated endotoxemic group was 31% at 48 h (p greater than 0.05, compared to the endotoxin + vehicle group).(ABSTRACT TRUNCATED AT 250 WORDS)