Regulation of glycolytic intermediates in cockroach fat body by the corpus cardiacum

Glycolytic intermediates and related metabolites were measured in the fat body of the American cockroach (Periplaneta americana) to locate the rate-limiting reactions that regulate glycolysis during the action of the corpus cardiacum (CC) in vitro.

1.	The concentrations of glucose 1-phosphate, fructose 6-phosphate, and fructose 1,6-bisphosphate were approximately doubled after 30 min treatment with CC extract, whereas that of glucose 6-phosphate increased more than four-fold. Slightly lower increases occurred after 10 and 60 min treatment.
2.	Triose phosphates, 2-phosphoglyceric acid, phosphoenolpyruvate and pyruvate were unaffected by CC extract.
3.	Glycerol 3-phosphate, which is 202-200 times more concentrated than any of the other measured metabolites in the unstimulated tissue, is increased more than two-fold by CC extract.
4.	NAD, NADP, and ATP were not significantly affected by CC extract. ADP was increased significantly by the gland extract.