Dependency of microdissected nephron segments upon oxidative phosphorylation and exogenous substrates: a relationship between tubular anatomical location in the kidney and metabolic activity.

1. In order to examine the possibility of heterogeneity in the dependence of renal tubular cells upon oxidative phosphorylation and exogenous substrates, the effects of antimycin A and substrate deprivation on adenosine 5'-triphosphate (ATP) content were examined in isolated rat nephron segments in vitro at 37 degrees C. 2. Antimycin A (5 mumol/l) caused varying decrements in cell ATP level within 5 min in the following order: proximal tubules greater than cortical thick ascending limb of Henle's loop (cTAL) greater than cortical collecting duct (cCD) in the cortex, and thin descending limb of Henle's loop (TDL) greater than medullary thick ascending limb of Henle's loop (mTAL) greater than outer medullary collecting duct (omCD) in the inner stripe of the outer medulla. In the thick ascending limb and the collecting duct, the segments located in the cortex were more sensitive than those in the medulla. 3. Substrate deprivation for 30 min markedly decreased the cell ATP content in cortical and medullary proximal tubules and also in medullary TDL, whereas it caused only a slight decrease in cTAL and mTAL with no change in cCD and omCD. 4. Media made hypertonic by the addition of 200 mmol/l NaCl under aerobic conditions, increased the requirement for exogenous substrates in TDL and mTAL, but not in omCD. This stimulation was seen to a lesser extent in media made hypertonic by the addition of mannitol instead of NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)