Expression and subcellular distribution of phosphoenolpyruvate carboxykinase in primary cultures of rabbit kidney proximal tubule cells: comparative study with renal and hepatic PEPCK in vivo

We previously reported a sex-specific effect of antenatal treatment with betamethasone (Beta) on sodium (Na+) excretion in adult sheep whereby treated males but not females had an attenuated natriuretic response to angiotensin-(1–7) [Ang-(1–7)]. The present study determined the Na+ uptake and nitric oxide (NO) response to low-dose Ang-(1–7) (1 pM) in renal proximal tubule cells (RPTC) from adult male and female sheep antenatally exposed to Beta or vehicle. Data were expressed as percentage of basal uptake or area under the curve for Na+ or percentage of control for NO. Male Beta RPTC exhibited greater Na+ uptake than male vehicle cells (433 ± 28 vs. 330 ± 26%; P < 0.05); however, Beta exposure had no effect on Na+ uptake in the female cells (255 ± 16 vs. 255 ± 14%; P > 0.05). Ang-(1–7) significantly inhibited Na+ uptake in RPTC from vehicle male (214 ± 11%) and from both vehicle (190 ± 14%) and Beta (209 ± 11%) females but failed to attenuate Na+ uptake in Beta male cells. Beta exposure also abolished stimulation of NO by Ang-(1–7) in male but not female RPTC. Both the Na+ and NO responses to Ang-(1–7) were blocked by Mas receptor antagonist d-Ala7-Ang-(1–7). We conclude that the tubular Ang-(1–7)-Mas-NO pathway is attenuated in males and not females by antenatal Beta exposure. Moreover, since primary cultures of RPTC retain both the sex and Beta-induced phenotype of the adult kidney in vivo they appear to be an appropriate cell model to examine the effects of fetal programming on Na+ handling by the renal tubules.

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Improved culture conditions stimulate gluconeogenesis in primary cultures of renal proximal tubule cells

AJP Cell Physiology ◽

10.1152/ajpcell.1995.268.4.c1053 ◽

1995 ◽

Vol 268 (4) ◽

pp. C1053-C1061 ◽

Cited By ~ 63

Author(s):

G. Nowak ◽

R. G. Schnellmann

Keyword(s):

Proximal Tubule ◽

Primary Cultures ◽

Lactate Production ◽

Glucose Production ◽

Renal Proximal Tubule ◽

Proximal Tubule Cells ◽

Tubule Cells ◽

Lactate Consumption ◽

Renal Proximal Tubule Cells

Unlike renal proximal tubule cells (RPTC) in vivo, RPTC cultured in standard conditions are hypoxic, glycolytic, and not gluconeogenic. This study investigated the effects of glucose and lactate on glycolysis and gluconeogenesis in rabbit RPTC cultured in conditions of increased oxygen supply (Shake). Confluent Shake cultures grown in the presence of glucose exhibited increased oxygen consumption and decreased glycolysis compared with stationary (Still) cultures. Addition of 5 mM lactate to a 5 mM glucose medium decreased net glucose consumption and glucose oxidation in Shake cultures by 34 and 50%, respectively, and resulted in net lactate consumption. Addition of 5 mM lactate to a glucose-free medium resulted in a threefold increase in net glucose production (0.024 +/- 0.003 vs. 0.074 +/- 0.013 mumol.mg protein-1.day-1) in Shake cultures. Net glucose production further increased to 0.430 +/- 0.020 and 1.640 +/- 0.040 mumol.mg protein-1.day-1 when glucose reuptake was inhibited by 1 mM phloridzin or 1 mM phloridzin + 1 mM phloretin, respectively. These results show that, under conditions of improved oxygenation and in the presence of lactate and physiological levels of glucose and insulin, RPTC aerobic metabolism increases and glucose metabolism changes from glycolysis and net lactate production to gluconeogenesis and net lactate consumption.

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Polarity and transport properties of rabbit kidney proximal tubule cells on collagen IV-coated porous membranes

AJP Renal Physiology ◽

10.1152/ajprenal.1995.269.1.f22 ◽

1995 ◽

Vol 269 (1) ◽

pp. F22-F30 ◽

Cited By ~ 1

Author(s):

I. Genestie ◽

J. P. Morin ◽

B. Vannier ◽

G. Lorenzon

Keyword(s):

Proximal Tubule ◽

Transport Properties ◽

Collagen Iv ◽

Transport Processes ◽

Rabbit Kidney ◽

Porous Membranes ◽

Proximal Tubule Cells ◽

Kidney Proximal Tubule ◽

Apical Compartment ◽

Tubule Cells

A high degree of functional polarity has been obtained in primary cultures of rabbit kidney proximal tubule cells grown on collagen IV-coated porous membranes. Tight confluency was attained 6 days after seeding and maintained for at least 6 more days, as shown by analysis of paracellular inulin diffusion. From day 6 onward, L-lactate, ammonia, and D-glucose concentration gradient and a pH difference of approximately 1 unit developed between the two nutrient medium compartments. Confluent monolayers expressed organic ion transport properties higher than those formerly reported for other cell models. Transcellular transport of 20 microM tetraethylammonium was directed from basal to apical compartment and was specifically inhibited by mepiperphenidol (1 mM). Unidirectional transport of 2.4 microM p-aminohippurate also occurred from basal to apical compartment, was saturable, and specifically inhibited by probenecid (1 mM). These results suggest that rabbit kidney proximal tubule cells, cultured under the experimental conditions described here, may be a useful model for the in vitro study of highly polarized renal transport processes.

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