The metabolic response of the canine neonate to twenty-four hours of fasting.
The metabolic effects of 24 hours of neonatal fasting in unanesthetized dogs were compared to fasting for three hours during the first day of life. Blood glucose, lactate, and ketones were unaltered while FFA (0.94 +/- 0.07 v 0.70 +/- 0.04 mmol/L, P less than .01), glycerol (0.21 +/- 0.01 v 0.12 +/- 0.01 mmol/L, P less than .01), and triglycerides (0.41 +/- 0.03 v 0.23 +/- 0.03 mmol/L, P less than .01) were lower at 24 hours. Glucose production and lactate and alanine turnover were unaffected while palmitate turnover declined (8.8 +/- 0.7 v 5.1 +/- 0.5 mumol/kg/min, P less than .01). Oxygen consumption decreased (6.9 +/- 0.4 v 6.0 +/- 0.3 mL/kg/min, P less than .02) while RQ increased (0.79 +/- 0.02 v 0.86 +/- 0.03, P less than 0.05) at 24 hours. Hepatic glycogen content declined (575 +/- 37 to 266 +/- 32 mumol/g, P less than .001) and could account for a GP of 12 mumol/kg/min between 3 and 24 hours of age. Both gluconeogenesis from lactate and alanine increased, together accounting for 7% and 21% of glucose production at 3 and 24 hours. The increment in gluconeogenesis may be facilitated by augmented hepatic cytosolic phosphoenolpyruvate carboxykinase at 24 hours (1.8 +/- 0.2 v 14.1 +/- 0.8 nmol/min mg protein, P less than .01). Despite the decline in VO2, hepatic ATP and energy charge were unaltered by 24 hours of fasting. These data suggest that FFA availability diminishes during a prolonged neonatal canine fast resulting in lower VO2. Furthermore, as FFA availability declines, glucose utilization becomes the predominant precursor for energy production.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002151:Calorimetry; D004285:Dogs; D005215:Fasting; D005941:Glucokinase / Q000378:metabolism; D005943:Gluconeogenesis; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism; D010101:Oxygen Consumption; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism
D007773:Lactates; D008112:Liver Glycogen; D019344:Lactic Acid; D005941:Glucokinase; D011770:Pyruvate Kinase; D010729:Phosphoenolpyruvate Carboxykinase (GTP)