The effect of phenylalanine on intracellular pH and sodium activity in proximal convoluted tubule cells of the frog kidney

1985 ◽  
Vol 404 (2) ◽  
pp. 145-149 ◽  
Author(s):  
G. Messner ◽  
A. Koller ◽  
F. Lang
Keyword(s):  
Intracellular Ph ◽  
Proximal Convoluted Tubule ◽  
Frog Kidney ◽  
Sodium Activity ◽  
Tubule Cells

Relationship between sodium transport and intracellular ATP in isolated perfused rabbit proximal convoluted tubule

1991 ◽  
Vol 261 (4) ◽  
pp. F634-F639 ◽  
Author(s):  
J. S. Beck ◽  
S. Breton ◽  
H. Mairbaurl ◽  
R. Laprade ◽  
G. Giebisch
Keyword(s):  
Potassium Channels ◽  
Cell Volume ◽  
Intracellular Ph ◽  
Sodium Transport ◽  
Sodium Pump ◽  
Basolateral Membrane ◽  
Potassium Conductance ◽  
Transference Number ◽  
Proximal Convoluted Tubule ◽  
A Cell

The effect of alterations in sodium transport on cell ATP content and pH in the isolated perfused proximal convoluted tubule (PCT) of the rabbit was examined. Stimulating sodium transport by the addition of luminal glucose and alanine decreased cell ATP from 4.44 +/- 0.93 to 2.69 +/- 0.62 mM (n = 4), increased intracellular pH by 0.13 +/- 0.02 (n = 7), and increased cell volume by 0.10 +/- 0.02 nl/mm (n = 4). Blocking the sodium pump with 10(-4) M strophanthidin in tubules in which sodium transport had been stimulated increased cell ATP from 2.04 +/- 0.24 to 2.42 +/- 0.32 mM (n = 6). In parallel experiments the same dose of strophanthidin depolarized the basolateral membrane from -52.6 +/- 1.9 to -6.4 +/- 1.6 mV, depolarized the transepithelial potential from -3.2 +/- 0.3 to -0.1 +/- 0.1 mV, and reduced the basolateral membrane potassium transference number from 0.47 to 0.26 indicating a reduction in basolateral potassium conductance. Since strophanthidin caused a cell alkalinization of 0.15 +/- 0.03, this latter effect cannot be due to changes of intracellular pH. Strophanthidin caused no change in cell volume over the period studied, suggesting that stretch-activated potassium channels are not involved either. Instead, potassium conductance inhibition may be the result of the closure of ATP-sensitive potassium channels. These same channels might thus be partly responsible for the increase in potassium conductance commonly observed during stimulation of sodium transport.

Intracellular pH regulation in cultured renal proximal tubule cells in different stages of maturation

1992 ◽  
Vol 263 (4) ◽  
pp. F716-F721 ◽  
Author(s):  
H. Ekblad ◽  
A. Aperia ◽  
S. H. Larsson
Keyword(s):  
Proximal Tubule ◽  
Intracellular Ph ◽  
Recovery Rate ◽  
Ph Regulation ◽  
Renal Proximal Tubule ◽  
Disulfonic Acid ◽  
Intracellular Acidosis ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells

This study examines the ontogeny of cellular pH regulation in renal proximal tubule cells (RPTC). RPTC from 8- to 40-day-old Sprague-Dawley rats (RPTC-8 to RPTC-40) were studied after 48 h of primary culture. Intracellular pH (pHi) was measured by quantitative fluorescence microscopy using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. Recordings were made under basal conditions and after imposing a cytoplasmic alkalosis and acidosis using 15 mM NH4+ salt. The net recovery rate (dpHi/dt) from intracellular acidosis increases significantly between 10 and 12 days of age from 0.39 +/- 0.04 to 0.54 +/- 0.06 pH units/min (P < 0.05, n = 10 vs. 6). This increase can be completely accounted for by an increase in the rate of amiloride (100 microM)-inhibitable Na(+)-H+ exchange (0.29 +/- 0.04 vs. 0.42 +/- 0.05 pH units/min, P < 0.05, n = 6 vs. 6). The rate of Na(+)-H+ exchange increases similarly in RPTC-10 and RPTC-40 when the transmembrane Na+ gradient is increased by Na+ depleting the cells (48 and 49%, respectively). The amiloride-insensitive recovery is Na+ independent and insensitive to 4-acetamido-4'-isothiocyanostilbene-2-2'-disulfonic acid (SITS, 500 microM) (range 0.08-0.14 pH units/min). The net recovery rate from intracellular alkalosis is significantly lower in RPTC-10 than in RPTC-40 (0.16 +/- 0.02 vs. 0.28 +/- 0.02 pH units/min, P < 0.01, n = 4 vs. 5). SITS (500 microM) inhibits the recovery by 27 +/- 8 and 26 +/- 9%, respectively, whereas amiloride has no effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal glucocorticoids stimulate neonatal juxtamedullary proximal convoluted tubule acidification

1991 ◽  
Vol 261 (5) ◽  
pp. F746-F752 ◽  
Author(s):  
M. Baum ◽  
R. Quigley
Keyword(s):  
Glucose Transport ◽  
Intracellular Ph ◽  
Proximal Convoluted Tubule ◽  
Proton Flux ◽  
Control Group ◽  
Urine Ph ◽  
Dexamethasone Group ◽  
Volume Absorption ◽  
In Vitro Microperfusion

The rate of neonatal proximal convoluted tubule (PCT) HCO3 absorption is lower than that of adult animals. The present in vitro microperfusion study examined whether prenatal dexamethasone (60 micrograms/kg daily to the doe for 3 days before delivery) would accelerate the maturation of neonatal juxtamedullary PCT acidification. Control neonates studied within 48 h of birth had a urine pH of 7.06 +/- 0.15 and a urine HCO3 concentration of 34.3 +/- 7.0 meq/l. Animals receiving dexamethasone had a urine pH of 6.47 +/- 0.11 and a urine HCO3 concentration of 10.1 +/- 4.0 meq/l, both of which were significantly lower than control (P less than 0.01). In juxtamedullary PCTs perfused in vitro, volume absorption was 0.27 +/- 0.03 nl.mm-1.min-1 in controls and 0.39 +/- 0.02 nl.mm-1.min-1 in dexamethasone-treated animals (P less than 0.05). HCO3 absorption was stimulated in the dexamethasone group (52.6 +/- 4.6 vs. 34.1 +/- 6.3 pmol.mm-1.min-1, P less than 0.05); however, glucose transport was not significantly affected (24.8 +/- 1.3 in dexamethasone vs. 21.5 +/- 3.5 pmol.mm-1.min-1 in controls). Intracellular pH was measured using 2',7'-bis(carboxyethyl)-5(6)-carboxyflourescin to examine whether prenatal dexamethasone stimulated the apical Na(+)-H+ antiporter and the basolateral Na(HCO3)3 symporter. Apical Na(+)-H+ antiporter proton flux was 108.5 +/- 14.2 pmol.mm-1.min-1 in the control group and 250.7 +/- 31.3 pmol.mm-1.min-1 in the dexamethasone group (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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