Effects of compound U74500A in animal models of gastric and duodenal ulceration

A lazaroid mitigates postresuscitation myocardial dysfunction

OBJECTIVE

Lazaroids, a series of 21-aminosteroids, reduce free radical mediated injury after ischemia and reperfusion. We hypothesized that the lazaroid U-74389G would minimize postresuscitation myocardial dysfunction and thereby improve neurologically meaningful survival in a rodent model after resuscitation from 8 mins of ventricular fibrillation.

DESIGN

Randomized, controlled laboratory study.

SETTING

University-affiliated research institute.

SUBJECTS

Sprague-Dawley rats.

INTERVENTIONS

Ventricular fibrillation was electrically induced in ten anesthetized Sprague-Dawley rats. The lazaroid agent U-74389G in a dose of 1 mg.kg-1 or its vehicle serving as a placebo was injected into the right atrium after 7 mins of untreated ventricular fibrillation. One minute after injection of the compound, precordial compression was begun together with mechanical ventilation and continued for 6 mins before attempted electrical defibrillation.

MEASUREMENTS AND MAIN RESULTS

All animals were successfully resuscitated. Postresuscitation cardiac index, left ventricular end-diastolic pressure, the rate of left ventricular pressure increase measured at a left ventricular pressure of 40 mm Hg, and the maximum rate of left ventricular pressure decline were significantly less impaired in lazaroid-treated animals. This contrasted with control animals, which had significantly greater myocardial impairment, greater neurologic deficit, and lesser duration of survival.

CONCLUSIONS

The lazaroid compound U-74389G, administered during cardiac arrest, mitigated postresuscitation myocardial dysfunction and improved survival.

Antioxidant activity of U-83836E, a second generation lazaroid, during myocardial ischemia/reperfusion injury

The 21-aminosteroid compounds are potent lipid peroxidation inhibitors belonging to a new class of antioxidants given the collective name of "lazaroids". They protect cells from oxidative damage induced by oxygen-based free radicals in a variety of in vitro and in vivo test systems. U-83836E is one of the second-generation lazaroids that are based on a non steroidal structure characterized by a ring portion of alpha-tocopherol bonded with various amine groups. We investigated the ability of U-83836E to reduce myocardial damage in rats undergoing left coronary artery occlusion for 60 min followed by 6 hours of reperfusion. This ischemia/reperfusion model produced wide heart necrosis, membrane lipid peroxidation, ventricular arrhythmias, tissue neutrophil infiltration and a marked decrease in endogenous antioxidants. Intravenous administration of U-83836E, (7.5, 15 and 30 mg/kg) at onset of reperfusion, reduced myocardial necrosis, expressed as a percentage of either the area at risk or the total left ventricle (p < 0.001), improved haemodynamic conditions by decreasing ventricular arrhythmias (p < 0.005), limited membrane lipid peroxidation (evaluated by assessing conjugated dienes, p < 0.001; and 4-hydroxynonenal, p < 0.001) restored the endogenous antioxidants vitamin E (p < 0.001), and superoxide dismutase (pt < 0.001). Furthermore, the lazaroid inhibited the derimental hydroxyl radical formation (p < 0.001), evaluated indirectly by a trapping agent and reduced heart neutrophil infiltration, measured by testing cardiac tissue elastase (p < 0.001) that is released from the stimulated granulocytes at the site of injury. These data suggest that this compound could be a new useful tool to study the mechanisms of oxidative damage during myocardial infarction.