Inhibition of lipolysis causes suppression of endogenous glucose production independent of changes in insulin.
We have shown that insulin controls endogenous glucose production (EGP) indirectly, via suppression of adipocyte lipolysis. Free fatty acids (FFA) and EGP are suppressed proportionately, and when the decline in FFA is prevented during insulin infusion, suppression of EGP is also prevented. The present study tested the hypothesis that suppression of lipolysis under conditions of constant insulin would yield a suppression of EGP. N(6)-cyclohexyladenosine (CHA) was used to selectively suppress adipocyte lipolysis during euglycemic clamps in conscious male dogs. FFA suppression by CHA caused suppression of EGP. Liposyn control experiments, which maintained FFA levels above basal during CHA infusion, completely prevented the decline in EGP, whereas glycerol control experiments, which maintained glycerol levels close to basal, did not prevent a decline in EGP. These controls suggest that the EGP suppression was secondary to the suppression of FFA levels specifically. A difference in the sensitivity of FFA and EGP suppression (FFA were suppressed approximately 85% whereas EGP only declined approximately 40%) was possibly caused by confounding effects of CHA, including an increase in catecholamine and glucagons levels during CHA infusion. Thus suppression of lipolysis under constant insulin causes suppression of EGP, despite a significant rise in catecholamines.
Mittelman
S D
SD
Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles 90089-9142, USA.
Bergman
R N
RN
D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002395:Catecholamines / Q000378:metabolism; D004285:Dogs; D004655:Emulsions; D005217:Fat Emulsions, Intravenous / Q000494:pharmacology; D005526:Food, Formulated; D005934:Glucagon / Q000378:metabolism; D005947:Glucose / Q000096:biosynthesis*; D015309:Glucose Clamp Technique; D007328:Insulin / Q000378:metabolism*; D054709:Lecithins; D008066:Lipolysis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D012450:Safflower Oil; D013024:Soybean Oil
D002395:Catecholamines; D004655:Emulsions; D005217:Fat Emulsions, Intravenous; D007328:Insulin; D054709:Lecithins; C031435:safflower oil, soybean oil, lecithin emulsion; C027513:N(6)-cyclohexyladenosine; D013024:Soybean Oil; D012450:Safflower Oil; D005934:Glucagon; D000262:Adenylyl Cyclases; D005947:Glucose; D000241:Adenosine