Kinetic characterization of 13NH3 and [13N]glutamine metabolism in rabbit heart.
The isolated arterially perfused rabbit interventricular septum was used to study the effects of methionine sulfoximine (MSO) on 13N-labeled ammonia (13NH3) and 13N-labeled glutamine [( 13N]gln) metabolism. Tissue time-activity curves were generated from bolus injections of 13NH3 or [13N]gln delivered interarterially during control conditions and in the presence of MSO. The fraction of 13N label retained in the tissue [EF(3)] was significantly (P less than 0.01) less after a bolus of [13N]gln than 13NH3. MSO significantly (P less than 0.05) decreased the EF(3) after a bolus of 13NH3 or [13N]gln. Chemical analyses using high-pressure liquid chromatography on tissue and effluent samples obtained after bolus injections of 13NH3 and [13N]gln with or without MSO present showed the following: 1) after a bolus of 13NH3 or [13N]gln the tissue 13N label is predominantly in [13N]gln at 6 min after injection, and 2) MSO significantly decreases the synthesis of [13N]gln after an 13NH3 bolus. Thus it would appear that the glutamine synthetase reaction is primarily responsible for the retention of the 13N label from 13NH3 as [13N]gln in rabbit myocardium.
D000641:Ammonia / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005973:Glutamine / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008717:Methionine Sulfoximine / Q000494:pharmacology; D009206:Myocardium / Q000032:analysis / Q000378:metabolism*; D009590:Nitrogen Radioisotopes; D011817:Rabbits
D009590:Nitrogen Radioisotopes; D005973:Glutamine; D008717:Methionine Sulfoximine; D000641:Ammonia