A B S T R A C T Unilateral ureter obstruction in rabbits produced profound changes in endogenous and exogenous renal arachidonic acid metabolism. Isolated perfused hydronephrotic kidneys (removed after 3 or 10 d of ureter obstruction) responded to bradykinin stimulation with a markedly enhanced release of prostaglandin E2 and thromboxane A2. Reversal (3 or 10 d) of the ureter obstruction resulted in a reduction in the vasoactive peptide-induced release of prostaglandin E2 and thromboxane A2 from the perfused hydronephrotic kidney. However, postobstruction reversal of prostaglandin production by the agonist-stimulated perfused kidney was not reflected in the cortical microsomal cyclooxygenase activity, which is greatly enhanced during ureter obstruction and does not decrease after removal of the obstruction. Histological analysis of the renal cortex in rabbits with ureteral obstruction revealed a proliferation of fibroblast-like cells and the presence of mononuclear cells; removal of the obstruction did not result in a disappearance of cortical fibroblasts but did result in a decrease of monocytes. The critical involvement of mononuclear cells in the exaggerated arachidonate metabolism that occurs during hydronephrosis was exhibited by the dem- onstration that: (a) only the perfused hydronephrotic rabbit kidney responded to administration of endotoxin with a sustained release of prostaglandin E2 and thromboxane A2; (b) the contralateral rabbit kidney, which is devoid of mononuclear cells, did not respond to endotoxin; and (c) the hydronephrotic cat kidney, which exhibits a fibroblast proliferation with a low number of mononuclear cells, did not respond to endotoxin. Thus, proliferation of fibroblast-like cells and the presence of mononuclear cells appear to be involved in the exaggerated prostaglandin and thromboxane production underlying hydronephrosis. The increase in microsomal cyclooxygenase activity is apparently most closely correlated with the increased fibroblastic activation and cellularity, whereas mononuclear cells (possibly via monokines) seem to be critical for the markedly enhanced prostaglandin and thromboxane release induced by endotoxin and bradykinin.
SUMMARY. Thromboxane A 2 is not produced in normal rabbit kidneys, but its synthesis is induced in numerous renal pathological states. The presence of this potent vasoconstrictor could readily compromise renal hemodynamics. We found that the thromboxane synthetase inhibitor, OKY-1581 (sodium-3-[4,3-pyridylmethyl)phenyI]-2-methylacrylate) is effective in the perfused hydronephrotic kidney in selectively inhibiting thromboxane production without altering prostaglandin E2 or prostacyclin release. The vasoactive peptides bradykinin and angiotensin cause the hydronephrotic kidney to produce thromboxane A2, which results in a profound renal vasoconstriction which is reversed by pretreatment with OKY-1581. Thus, OKY-1581 provides a powerful tool which can be used to assess the participation of thromboxane in pathophysiological states and to ascertain the therapeutic potential of thromboxane synthetase inhibitors in numerous disease states. (Circ Res 50: [486][487][488][489][490] 1982)
Abstract-The effects of (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid (OKY-046) on thromboxane A2 (TXA2) synthetase in vitro and on experimental animal models of sudden death and cerebral infarction were studied.
Abstract-The effect of ONO-3307 (4-sulfamoyl phenyl-4-guanidinobenzoate methanesulfonate), a new protease inhibitor, was studied on various proteases in vitro and in an experimental thrombosis model in vivo. ONO-3307 competitively inhibited trypsin, thrombin, plasma kallikrein, plasmin, pancreatic kallikrein and chymotrypsin; and their Kj values were 0.048 ,uM, 0.18 flM, 0.29 jiM, 0.31 uM, 3.6 ,uM and 47 jiM, respectively. In addition, ONO-3307 inhibited both elastase release from N-formyl-Met-I-eu-Phe (fMLP) -stimulated leukocytes and tissue thromboplastin release from endotoxin-stimulated leukocytes. To examine the effects of ONO-3307 on disseminated intravascular coagulation (DIC), we de veloped an experimental thrombosis model. ONO-3307 (10 mg/kg/hr) completely inhibited the deposition of radioactive fibrin in kidney and lung. Gabexate mesilate (50 mg,/kg/hr) was also effective in this model, but the effect of nafamostat mesilate was unclear. These results indicate that ONO-3307 exhibits a wide range of inhibitory effects on various proteases, and ONO-3307 may be useful for the treat ment of protease-mediated diseases such as thrombosis and DIC.
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