Effects of Fasting on Adipose Tissue Perfused in Situ in Young Dogs

The effect of starvation on blood flow and uptake or release of oxygen, glucose, lactate, pyruvate, free fatty acids, glycerol, acetoacetate, and β-hydroxybutyrate was studied in isolated inguinal canine subcutaneous adipose tissue. In adipose tissue to which the sympathetic nerve was sectioned, blood flow in fed and in starved dogs did not differ significantly, when expressed per fat pad. Also, there was no difference in the effect of stimulation of the sectioned nerve's distal end or of theophylline infusion. Adipose tissue glucose and oxygen uptake was similar in fed and starved dogs, amounting to 4 and 10 μmols · min−1 · 100 g−1 respectively. In the starved dogs, as many carbon atoms were released in the form of lactate and pyruvate as were taken up in the form of glucose, whereas in the fed dogs the observed glucose uptake could more than account for the observed oxygen uptake, lactate release, and re-esterification. Compared to fed control dogs, lipolysis in starved dogs was increased fourfold (p < 0.005) under basal conditions, but essentially the same lipolytic response was seen following nerve stimulation and maximal stimulation with theophylline.