Effects of L-glutamine on post-ischaemic cardiac function: protection and rescue.
We investigated the effects of L-glutamine (0-20 mM) on cardiac function. The isolated perfused working rat heart (left atrial and aortic pressures of 5 and 70 cm H2O, respectively) was subjected to 20 min of normothermic low-flow ischaemia followed by reperfusion for 35 min. In the absence of glutamine, ischaemia-reperfusion caused an immediate significant (P < 0.01) fall in cardiac output from 46 to 20 ml/min, with a further deterioration to 17 ml/min at 35 min reperfusion. Ischaemia also caused a significant (P < 0.05) fall in myocardial glutamate from 2.6 to 1.8 mumol/g wet weight; and ischaemia-reperfusion caused significant (each P < 0.05) diminutions of myocardial ATP from 3.5 to 1.0 mumol/g wet weight and phosphocreatine from 4.8 to 1.5 mumol/g wet weight and resulted in significant (P < 0.05) accumulation of myocardial lactate from 0.9 to 4.3 mumol/g wet weight. Glutamine, present throughout the perfusion protocol (i.e. prior to ischaemia), at or above 1.25 mM, prevented the post-ischaemic diminution of cardiac output and the deleterious changes in myocardial metabolites. Post-ischaemic treatment with glutamine at 2.5 mM completely prevented the post-ischaemic diminution of cardiac output and restored the myocardial metabolites to normal.


CONCLUSIONS
Glutamine may be suitable as a cardioprotective and rescue agent. These effects may be mediated by maintenance of myocardial glutamate, ATP and phosphocreatine: and prevention of lactate accumulation.
Khogali
S E
SE
Department of Anatomy & Physiology, University of Dundee, Scotland, UK.
Harper
A A
AA
Lyall
J A
JA
Rennie
M J
MJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D000409:Alanine / Q000378:metabolism; D000818:Animals; D002302:Cardiac Output; D005971:Glutamates / Q000378:metabolism; D005972:Glutaminase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism / Q000494:pharmacology*; D007773:Lactates / Q000378:metabolism; D008297:Male; D017202:Myocardial Ischemia / Q000378:metabolism / Q000517:prevention & control* / Q000628:therapy; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014867:Water / Q000378:metabolism
D005971:Glutamates; D007773:Lactates; D010725:Phosphocreatine; D014867:Water; D005973:Glutamine; D000255:Adenosine Triphosphate; D005972:Glutaminase; D000409:Alanine