Fructose 2,6-bisphosphate levels and modulation of glycolysis by histamine, cholecystokinin, and forskolin in isolated rabbit gastric glands.
In isolated rabbit gastric glands incubated in the presence of 1 mmol/L glucose, the content of fructose 2,6-bisphosphate (F-2,6-P2) was 5.7 +/- 0.5 pmol/mg dry weight. This value was progressively incremented by increasing glucose concentration in the incubation medium, and was almost doubled at 10 mmol/L glucose. Under these conditions, a close correlation could be established between the levels of F-2,6-P2 and the rate of L-lactate formation (r = .98; P less than .05). Both histamine (0.1 mmol/L) and cholecystokinin octapeptide (CCK-OCT; 0.1 mumol/L) increased L-lactate production, without significant changes in either F-2,6-P2 concentration or the amount of 6-phosphofructo-2-kinase in active form. In contrast, forskolin, which markedly increased the glandular content of cyclic adenosine monophosphate (cAMP), partially blocked glucose consumption and caused a significant reduction in both F-2,6-P2 levels and the proportion of 6-phosphofructo-2-kinase in active form. Furthermore, forskolin partially blocked the rate of glucose uptake by isolated gastric glands. Our results suggest a regulatory role of F-2,6-P2 in the control of the glycolytic flux in response to glucose, but not in its response to histamine or CCK-OCT.
Rossi
I
I
Servicio de Gastroenterología, Hospital Puerta de Hierro, Facultad de Medicina, Universidad Autónoma de Madrid, Spain.
Olea
J
J
Herias
M
M
Pereda
C
C
Felíu
J E
JE
D019325:3-O-Methylglucose; D000818:Animals; D005576:Colforsin / Q000031:analogs & derivatives / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D005635:Fructosediphosphates / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D008757:Methylglucosides / Q000378:metabolism; D010435:Pepsinogens / Q000378:metabolism; D025481:Phosphofructokinase-2; D010770:Phosphotransferases / Q000378:metabolism; D011817:Rabbits; D012844:Sincalide / Q000494:pharmacology*
D005635:Fructosediphosphates; D007773:Lactates; D008757:Methylglucosides; D010435:Pepsinogens; D019325:3-O-Methylglucose; D005576:Colforsin; C027652:fructose 2,6-diphosphate; D006632:Histamine; D000242:Cyclic AMP; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D005947:Glucose; D012844:Sincalide; C047983:1,9-dideoxyforskolin