title: Metabolism of nitrogen-13 labelled ammonia in different conditions in dogs, human volunteers and transplant patients.
abstract: To investigate the rate of metabolism of nitrogen-13 labelled ammonia (13NH3) in different conditions, we have determined the relative amount of unchanged 13NH3 in the blood of dogs, volunteers and transplant patients at different times following injection. In dogs, the determinations were made under basal conditions, during adenosine administration and after coronary occlusion. The results show that adenosine administration increases the metabolic rate whereas coronary occlusion does not affect 13NH3 metabolism. For both human volunteers and transplant patients the metabolic rate of 13NH3 was assessed under basal conditions and during adenosine administration. 13NH3 metabolism proceeds faster in transplant patients than in volunteers under both conditions. Adenosine administration causes a faster 13NH3 turnover in volunteers but not in transplant patients. Application of individual metabolite correction resulted in a 16% decrease in the calculated blood flow compared to uncorrected values. A smaller difference (5%) was observed between correction with mean metabolite values and individually acquired metabolite values.
authors.affiliation: Laboratory of Radiopharmaceutical Chemistry FFW, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Bormans
authors.forename: A
authors.initials: A
authors.lastname: Maes
authors.forename: W
authors.initials: W
authors.lastname: Langendries
authors.forename: J
authors.initials: J
authors.lastname: Nuyts
authors.forename: M
authors.initials: M
authors.lastname: Vrolix
authors.forename: J
authors.initials: J
authors.lastname: Vanhaecke
authors.forename: C
authors.initials: C
authors.lastname: Schiepers
authors.forename: M
authors.initials: M
authors.lastname: De Roo
authors.forename: L
authors.initials: L
authors.lastname: Mortelmans
authors.forename: A
authors.initials: A
authors.lastname: Verbruggen
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000328:Adult; D000641:Ammonia / Q000097:blood; D000818:Animals; D003326:Coronary Circulation; D003327:Coronary Disease / Q000000981:diagnostic imaging; D004285:Dogs; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D016027:Heart Transplantation / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D009590:Nitrogen Radioisotopes; D014055:Tomography, Emission-Computed
chemical_list: D009590:Nitrogen Radioisotopes; D000641:Ammonia; D000241:Adenosine