Souza-Fiho M V, Lima M V, Pompeu M M, Ballejo G, Cunha F Q, Ribeiro R de A
Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza, Ribeirão Preto, Brazil.
Am J Pathol. 1997 Jan;150(1):247-56.
The involvement of nitric oxide (NO) and the potential modulation of NO synthase (NOS) activity by platelet-activating factor were investigated in a rat model of cyclophosphamide-induced hemorrhagic cystitis. Male Wistar rats received a single intraperitoneal injection of cyclophosphamide, and cystitis was evaluated 6, 12, 24, 48, and 72 hours later by determining the changes in bladder wet weight and plasma protein extravasation and the macro- and microscopic morphological alterations. In addition, NOS activity and NADPH-diaphorase histochemistry were studied in bladder tissues. Normal bladders showed extensive NADPH-diaphorase staining and a high level of constitutive NOS whereas the activity of inducible NOS was almost undetectable. Cyclophosphamide dose- and time-dependently increased the bladder wet weight and bladder plasma protein extravasation. These events were accompanied at a microscopic level by urothelial necrosis, sloughing, ulceration, hemorrhage, and leukocyte infiltration. Cyclophosphamide also increased the levels of inducible NOS but reduced those of constitutive NOS. The NOS inhibitors L-NG-nitroarginine methyl ester and L-NG-nitroarginine significantly reduced the cyclophosphamide-induced plasma protein extravasation and urothelial damage. This reduction was completely reversed by L-arginine but not by D-arginine. The administration of the platelet-activating factor antagonist BN 52021 decreased the cyclophosphamide-induced plasma protein extravasation as well as the rise in inducible NOS activity but had no effect on the fall in constitutive NOS activity. These results suggest that endogenous NO participates in the urothelial damage and in the inflammatory events leading to cyclophosphamide-induced hemorrhagic cystitis. Platelet-activating factor also seems to be involved in the pathogenesis of this condition, possibly by inducing NOS.
在环磷酰胺诱导的出血性膀胱炎大鼠模型中，研究了一氧化氮（NO）的参与情况以及血小板活化因子对一氧化氮合酶（NOS）活性的潜在调节作用。雄性Wistar大鼠单次腹腔注射环磷酰胺，在6、12、24、48和72小时后，通过测定膀胱湿重变化、血浆蛋白外渗以及大体和微观形态学改变来评估膀胱炎。此外，还研究了膀胱组织中的NOS活性和NADPH-黄递酶组织化学。正常膀胱显示广泛的NADPH-黄递酶染色和高水平的组成型NOS，而诱导型NOS的活性几乎检测不到。环磷酰胺剂量和时间依赖性地增加膀胱湿重和膀胱血浆蛋白外渗。在微观水平上，这些事件伴随着尿路上皮坏死、脱落、溃疡、出血和白细胞浸润。环磷酰胺还增加了诱导型NOS的水平，但降低了组成型NOS的水平。NOS抑制剂L-NG-硝基精氨酸甲酯和L-NG-硝基精氨酸显著降低了环磷酰胺诱导的血浆蛋白外渗和尿路上皮损伤。L-精氨酸可完全逆转这种降低，但D-精氨酸则不能。给予血小板活化因子拮抗剂BN 52021可降低环磷酰胺诱导的血浆蛋白外渗以及诱导型NOS活性的升高，但对组成型NOS活性的降低没有影响。这些结果表明内源性NO参与了尿路上皮损伤以及导致环磷酰胺诱导的出血性膀胱炎的炎症事件。血小板活化因子似乎也参与了这种疾病的发病机制，可能是通过诱导NOS。
