Substrate-turnover interrelationships in fasting neonatal dogs.

Substrate-turnover relationships were determined in unanesthetized healthy fasted neonatal dogs during the first day of life. Pups were born at term by cesarean section to starved or control mothers. Pups born to starved mothers developed significantly lower blood glucose concentrations during neonatal fasting. In all pups, blood glucose concentrations during neonatal fasting. In all pups, blood glucose concentrations correlated to glucose utilization (r = 0.462, P < 0.001). Blood lactate concentration was significantly related to its turnover. The relationship between lactate turnover and lactate carbon appearance into glucose was significantly correlated. However, the relationship between lactate concentration and its carbon incorporation into glucose was only significant at 24 h of age in pups born to starved mothers. These data suggest that the neonatal dog is capable of regulating its glucose and lactate utilization by the availability of substrate. Because peripheral insulin levels correlated poorly to fasting blood glucose and glucose turnover; it is doubtful whether insulin secretion plays a significant role in fasting neonatal canine glucose homeostasis.