AJP - Heart and Circulatory Physiology, Vol 246, Issue 2 267-H273, Copyright © 1984 by American Physiological Society
Kinetic characterization of 13NH3 and [13N]glutamine metabolism in rabbit heart
J. Krivokapich, J. R. Barrio, M. E. Phelps, C. R. Watanabe, R. E. Keen, H. C. Padgett, A. Douglas and K. I. Shine
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.
