Gluconeogenesis in isolated nephron segments of the rabbit.

Glucose production rates from lactate and pyruvate in individually isolated segments of the rabbit nephron were measured using the enzymatic cycling method. Glucose production per mm length was uniformly high in the whole proximal tubule including the straight descending portion. Lower values were observed in the thin descending limb and in the thick ascending limb of Henle's loop. We believe that this study demonstrates two advantages of the approach suggested by Burg and Orloff to study renal metabolism in different parts of the nephron: first, specific differences in the metabolism of indivudual nephron segments can be detected directly, second, metabolic rates are easily to be compared with physiological data obtained by micropuncture and microperfusion since the common point of reference is the length of the nephron segments.