title: Isolation and measurement of 15N2 from respiratory gases of animals administered 15N-labeled substances.
abstract: A method is described for collection of metabolic 15N2 from in vitro preparations or intact rats administered 15N-containing compounds. The methods enables routine collection and mass spectrometric measurement of as little as 10 mumol 15N2 respired by a rat over a 24-h period. A device is described that includes either an animal chamber or a tissue reaction vessel in a closed recycling atmosphere, with automatic O2 replenishment and removal of CO2 and water. It is capable of sustaining moderate vacuum and is coupled to a high-vacuum manifold designed to process the contained atmosphere and respiratory gases. The starting atmosphere is an 80:20 mix of sulfur hexafluoride and O2. Recovery of 15N2 gas from the system without an animal present was 101.3 +/- 5.75%. When 15N2 gas was very slowly infused iv into an animal, recovery was 89.1 +/- 5.38%. Use of the method in studies of the fate of [15N]hydrazine in rats indicated that about 15% of the administered hydrazine is rapidly converted to 15N2, followed by slower conversion of an additional 7-10% over the next several hours.
mesh_terms: D000818:Animals; D001273:Atmosphere Exposure Chambers; D008297:Male; D013058:Mass Spectrometry; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D009587:Nitrogen Isotopes; D051381:Rats; D011919:Rats, Inbred Strains; D012137:Respiratory System / Q000378:metabolism*
chemical_list: D009587:Nitrogen Isotopes; D009584:Nitrogen