EFFECTS OF L-NAME AND L-ARGININE ON DIAPHRAGM CONTRACTION IN A SEPTICANIMAL-MODEL

The effects of nitric oxide on diaphragm contraction after endotoxin a dministration were studied in Wistar rats. The animals were divided in to seven treatments: a saline injected group as control, three groups injected with L-NAME (0.01, 0.1, 1 mg/kg) and three groups injected wi th L-arginine (1, 10, 100 mg/kg). Escherichia coli endotoxin was injec ted into the peritoneal cavity 15 min later. Twitch kinetics and force -frequency curves were measured 0, 2, and 4 hr after endotoxin injecti on. In the control group, the force-frequency curves significantly dec reased from 0 hr to 4 hr. In the L-NAME group, the force-frequency cur ves at 4 hr showed significant increases in a dose-dependent manner. I n the L-arginine group, the force-frequency curve with 100 mg/kg at 4 hr showed a significant increase. There was no consistent change in th e contraction time, half relaxation time, or fatiguability. NADPH diap horase histochemistry performed on diaphragm muscle samples 4 hr after endotoxin injection showed positive in the control and L-arginine gro up, but was only weakly observed in L-NAME group. These data suggest t hat nitric oxide contributes to the endotoxin induced diaphragm contra ctile deterioration COME BIOCHEM PHYSIOL 119A;1:219-224, 1998. (C) 199 8 Elsevier Science Inc.