The relationship between intracellular CA2+ and the mitochondrial membrane potential in isolated proximal tubular cells from rat kidney exposed to the nephrotoxin 1,2-dichlorovinyl-cysteine

Adult male Sprague-Dawley rats were injected intraperitoneally with 5 U insulin/kg body wt (45 animals). As determined by quantitative electron microscopy, the volume fraction and the numerical density of autophagic vacuoles (AV) in proximal tubular cells decreased within 10 min by 46 and 26%, respectively. A partial recovery of the AV volume fraction was observed 20 and 30 min after the injection contrary to our previous findings with liver (J. Cell Biol. 78: 152-167, 1978). In an additional experiment (12 animals) it was shown that an insulin dose of 0.5 U but not of 0.05 U/kg body wt reduced the AV volume fraction to an extent similar to that of 5 U. To eliminate possible secondary effects, Ringer solution containing 0.8 microM insulin was dropped intravitally for 15 min to one pole of the decapsulated kidney and Ringer solution without additions to the other pole (8 animals). After intravital fixation, the AV volume fraction and numerical density in proximal tubular cells was found to be reduced under the influence of insulin by 22 and 36%, respectively. This data shows that insulin inhibits the process of cellular autophagy in proximal tubular cells of the kidney.

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Integrative effects of EGF on metabolism and proliferation in renal proximal tubular cells

AJP Cell Physiology ◽

10.1152/ajpcell.1995.269.5.c1317 ◽

1995 ◽

Vol 269 (5) ◽

pp. C1317-C1325 ◽

Cited By ~ 28

Author(s):

G. Nowak ◽

R. G. Schnellmann

Keyword(s):

Oxygen Consumption ◽

Acid Synthesis ◽

Proximal Tubular Cells ◽

Tubular Cells ◽

Proximal Tubular ◽

Epidermal Growth ◽

Renal Proximal Tubular Cells ◽

Renal Proximal Tubular ◽

The Relationship ◽

Stimulation Of

This study examined the relationship between alterations in cellular metabolism and induction of proliferation in renal proximal tubular cells (RPTC) after epidermal growth factor (EGF) exposure. EGF treatment (10 ng/ml) of confluent RPTC cultures for 6 consecutive days increased monolayer DNA content 3.3-fold. EGF-stimulated proliferation of RPTC was preceded by a rapid (within 4 h) induction of glycolysis and a decrease in basal and ouabain-sensitive oxygen consumption (20 and 30%, respectively). EGF stimulated the pentose cycle by 58% and decreased gluconeogenesis by 48%. Supplementation of the culture medium with ribose-5-phosphate or ribose abolished the stimulation of glycolysis and the pentose cycle by EGF but had no effect on proliferation. These results show that EGF rapidly stimulates the pentose cycle, shifts glucose metabolism from gluconeogenesis to glycolysis, and decreases oxygen consumption before any increase in proliferation. The lack of an EGF effect on the pentose cycle and glycolysis in the presence of exogenous precursors for DNA synthesis suggests that the stimulation of these pathways before proliferation is due to increased demands for ribose for subsequent nucleic acid synthesis.

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