Noninvasive measurement of exhaled nitric oxide in a spontaneously breathing mouse

Nitric oxide (NO) has been detected in the exhaled gas of animals and human s. In previous work, investigators have used anesthetized, mechanically ven tilated animals to obtain exhaled NO (E-NO) measurements, which has unclear effects on the levels of END and does not allow for repeated analysis of E -NO. We sought to measure E-NO from a single, spontaneously breathing mouse . The mouse was placed in a small Plexiglas chamber and allowed to acclimat ize before exhaled gas was collected for E-NO analysis. Under optimal opera ting conditions of flow and pressure, the mean concentration of exhaled NO (FENO) Of 25 mice was 10.1 +/- 1.0 ppb. The maximal variation of FEND when repeatedly measured daily in individual animals was 2.1 ppb. Administration of L-NAME, a nonselective NOS inhibitor, reduced FENO by 51 +/- 6% (p < 0. 01). Intraperitoneally administered lipopolysaccharide induced acute lung i njury and increased FENO by 30 +/- 7% (p < 0.05). We have demonstrated that it is possible to noninvasively measure E-NO from a single, spontaneously breathing mouse. This novel technique provides a stable, reproducible, and responsive measure of E-NO in mice. This technique will be of use in determ ining cellular and isoform sources of E-NO, as well as the role of endogeno us NO in lung disease.