Metabolite utilization and compartmentation in porcine carotid artery: a study using beta-guanidinopropionic acid.
The relationship between substrate and metabolism in vascular smooth muscle has been investigated by studying the acute energetic effects caused by the creatine analogue beta-guanidinopropionic acid (beta-GPA) on porcine carotid arteries using 31P-nuclear magnetic resonance (NMR). Porcine carotid arteries were superfused for 12 h with Krebs-Henseleit buffer at 22 degrees C, containing 50 mM beta-GPA, and either 11 mM glucose or 5 mM pyruvate as substrate. beta-GPA enters the cells and becomes phosphorylated by creatine kinase to produce beta-GPA-P. Perfusion with beta-GPA leads to the formation of NMR observable beta-GPA-P (after 2.5 h). The appearance of beta-GPA-P with time was significantly greater when glucose was used as substrate. To differentiate between oxidative and glycolytic metabolism in the phosphorylation of beta-GPA, 1 mM cyanide was included in the perfusion buffer containing 50 mM beta-GPA and 11 mM glucose. No phosphocreatine (PCr) was observed with these conditions, and there was a small but significant decrease in ATP concentration ([ATP]) compared with glucose perfusion without cyanide (0.56 +/- 0.02 to 0.47 +/- 0.02 mumol/g wet wt), that was greater than the concentration with pyruvate as substrate (0.25 +/- 0.03 mumol/g wet wt). Thus the [ATP] during cyanide treatment is maintained with glycolytic metabolism. Despite the relatively high [ATP], accumulation of beta-GPA-P only occurred over a much slower time course ( > 10 h) than without cyanide.(ABSTRACT TRUNCATED AT 250 WORDS)
Boehm
E A
EA
Department of Biochemistry, University of Oxford, United Kingdom.
Clark
J F
JF
Radda
G K
GK
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002339:Carotid Arteries / Q000187:drug effects / Q000378:metabolism*; D003486:Cyanides / Q000494:pharmacology; D006146:Guanidines / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D010725:Phosphocreatine / Q000378:metabolism; D010766:Phosphorylation; D011422:Propionates / Q000378:metabolism / Q000494:pharmacology*; D013552:Swine
D003486:Cyanides; D006146:Guanidines; D007773:Lactates; D011422:Propionates; D010725:Phosphocreatine; D019344:Lactic Acid; D000255:Adenosine Triphosphate; C005775:guanidinopropionic acid