Mitochondrial F(1)F(0)-ATPase normally synthesizes ATP in the heart, but under ischemic conditions this enzyme paradoxically causes ATP hydrolysis. Nonselective inhibitors of this enzyme (aurovertin, oligomycin) inhibit ATP synthesis in normal tissue but also inhibit ATP hydrolysis in ischemic myocardium. We characterized the profile of aurovertin and oligomycin in ischemic and nonischemic rat myocardium and compared this with the profile of BMS-199264, which only inhibits F(1)F(0)-ATP hydrolase activity. In isolated rat hearts, aurovertin (1-10 microM) and oligomycin (10 microM), at concentrations inhibiting ATPase activity, reduced ATP concentration and contractile function in the nonischemic heart but significantly reduced the rate of ATP depletion during ischemia. They also inhibited recovery of reperfusion ATP and contractile function, consistent with nonselective F(1)F(0)-ATPase inhibitory activity, which suggests that upon reperfusion, the hydrolase activity switches back to ATP synthesis. BMS-199264 inhibits F(1)F(0) hydrolase activity in submitochondrial particles with no effect on ATP synthase activity. BMS-199264 (1-10 microM) conserved ATP in rat hearts during ischemia while having no effect on preischemic contractile function or ATP concentration. Reperfusion ATP levels were replenished faster and necrosis was reduced by BMS-199264. ATP hydrolase activity ex vivo was selectively inhibited by BMS-199264. Therefore, excessive ATP hydrolysis by F(1)F(0)-ATPase contributes to the decline in cardiac energy reserve during ischemia and selective inhibition of ATP hydrolase activity can protect ischemic myocardium.

No abstract

No abstract

Vasopeptidase inhibitors are single molecules that inhibit neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) simultaneously. Omapatrilat, the first in this new class of cardiovascular agents, potentiates vasodilatory and cardioprotective peptides and represses angiotensin II. This study compared the effects of omapatrilat with those of a pure ACE inhibitor on cardiac geometry and survival in animals with heart failure. BIO TO-2 cardiomyopathic hamsters (CMHs) in the early stages of dilated heart failure were treated with vehicle or maximal ACE inhibitory doses of captopril (750 micromol/kg/day) or omapatrilat (200 micromol/kg/day). Prolonged vasopeptidase inhibition increased median survival time after the start of treatment by 99 and 31% compared with vehicle and captopril, respectively (median survival times: 146, 221, and 290 days with vehicle, captopril, and omapatrilat, respectively; p < 0.001 for all comparisons). In similar CMHs, captopril or omapatrilat administered for 2 months significantly (p < 0.05) decreased heart weight, pulmonary congestion (lung weight), and left ventricular (LV) chamber volume compared with vehicle. Omapatrilat significantly increased LV mass-to-volume ratio compared with vehicle and captopril. Omapatrilat, but not captopril, significantly increased urinary atrial natriuretic peptide excretion, indicating NEP inhibition. Thus vasopeptidase inhibition with omapatrilat was more effective than ACE inhibition with captopril in preventing changes in LV geometry and premature mortality in hamsters with dilated heart failure.

No abstract

No abstract

No abstract

Rodents are commonly used for inhalation toxicology studies, but until recently the nasal passages have often been overlooked or only superficially examined. The rodent nose is a complex organ in which toxicant-induced lesions may vary, depending on the test compound. A working knowledge of rodent nasal anatomy and histology is essential for the proper evaluation of these responses. Lack of a systematic approach for examining rodent nasal tissue has led to a paucity of information regarding nonneoplastic lesions in the rodent nose. Therefore, slides from the National Toxicology Program (NTP) and the Chemical Industry Institute of Toxicology (CIIT) were examined, and the literature was reviewed to assemble the spectrum of nonneoplastic rodent nasal pathology. Presented are lesions associated with the various types of epithelia lining the rodent nasal cavity plus lesions involving accessory nasal structures. Even though there are anatomic and physiologic differences between the rodent and human nose, both rats and mice provide valuable animal models for the study of nasal epithelial toxicity, following administration of chemical compounds.