Glucose uptake and amino acid metabolism in perfused hearts from tumor-bearing rats.
The purpose of this study was to evaluate whether heart glucose metabolism can account for elevated heart oxygen consumption in a tumor-bearing host. This is the first report of altered metabolism in perfused hearts from tumor-bearing animals. Glucose, glycerol, lactate, and amino acid metabolism was examined under steady-state conditions in isolated perfused hearts from sarcoma-bearing rats and compared to the metabolism in hearts from starved (96 hr) and fed control rats. Heart dry weight was reduced by 10% in tumor-bearing rats and by 30% in starved rats when compared to freely fed control animals. Cardiac glucose uptake was decreased in tumor-bearing rats (206 +/- 33 mumoles/hr/g dry wt) compared to both starved (298 +/- 18) and fed control rats (293 +/- 25). Hearts from both fed and starved controls released lactate and glycerol at significant rates during perfusion which was not evident in hearts from tumor-bearing rats. The release of individual amino acids from working hearts during perfusion was different among the animal groups with a severe depression of both glutamine and alanine release in tumor-bearing rats. In starved rats alanine release was normal although glutamine release was depressed by more than 50%. The net release of all amino acids was lowest in hearts from tumor-bearing rats, intermediate in the starved animals, and highest in the control animals, while the nonmetabolized amino acids (phenylalanine, tyrosine, methionine) were released at increased rates only from tumor-host hearts, indicating an increased net breakdown of some cardiac proteins in tumor-bearing animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Drott
C
C
Department of Surgery, University of Gothenburg, Sweden.
Lundholm
K
K
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D005947:Glucose / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012513:Sarcoma, Experimental / Q000378:metabolism*
D000596:Amino Acids; D005947:Glucose