Calcium homeostasis: The effect of parathyroid hormone on bone membrane electrical potential difference

1985 ◽  
Vol 37 (3) ◽  
pp. 307-311 ◽  
Author(s):  
D. R. Peterson ◽  
W. J. Heideger ◽  
K. W. Beach
Keyword(s):  
Parathyroid Hormone ◽  
Calcium Homeostasis ◽  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Membrane Electrical Potential

Bicarbonate reabsorption and electrophysiology of proximal tubules in uninephrectomized rats

1991 ◽  
Vol 81 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Dirce M. Zanetta Limongi ◽  
Antonio Carlos Cassola ◽  
Viktoria Woronik ◽  
Gerhard Malnic
Keyword(s):  
Basolateral Membrane ◽  
Electrical Potential ◽  
Ringer Solution ◽  
Proximal Tubules ◽  
Potential Difference ◽  
Protonmotive Force ◽  
Electrical Potential Difference ◽  
Analogue Model ◽  
Significant Difference ◽  
Membrane Electrical Potential

1. The kinetics of acidification of luminal fluid in hypertrophied proximal tubules after unilateral nephrectomy was studied by stationary microperfusion and continuous measurement of luminal pH with antimony microelectrodes. 2. Trans-epithelial and basolateral membrane electrical potential differences were measured in order to detect modifications in electrogenic transport mechanisms under these conditions. 3. The values of stationary pH and HCO−3 concentration were significantly lower, the mean acidification half-time was not different and net reabsorptive HCO−3 fluxes in proximal tubules were significantly increased in uninephrectomized rats. According to an electrical analogue model, these results suggest (a) a reduction in the internal series resistance of the H+ pump, caused perhaps by an increased density of pump sites, and (b) an increase in the protonmotive force of the pump. 4. The trans-epithelial electrical potential difference measured in free flow conditions was significantly more lumen-positive in uninephrectomized rats. The trans-epithelial electrical potential difference measured during intraluminal perfusion with Ringer solution containing 30 mmol/l HCO−3 was significantly more negative in all groups studied. In uninephrectomized rats treated with acetazolamide, the trans-epithelial electrical potential difference was more lumen-negative than that in untreated uninephrectomized rats. These results are compatible with a steeper transepithelial Cl− gradient as well as with electrogenic, active H+ secretion. 5. There was no significant difference in the basolateral electrical potential difference between control and uninephrectomized rats. 6. In conclusion, our data show an increase in the transport rates of HCO−3 in the proximal tubule of uninephrectomized rats, which may be due to an increase in the density of transporters in the brush-border membrane, and an increased ability of the transport mechanism to create H+ gradients.

scholarly journals Transmural electrical potential difference in the mammalian esophagus in vivo

1978 ◽  
Vol 75 (2) ◽  
pp. 286-291 ◽  
Author(s):  
Keith S. Turner ◽  
Don W. Powell ◽  
Charles N. Carney ◽  
Roy C. Orlando ◽  
Eugene M. Bozymski
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference

Electrical potential difference between exocelomic fluid and maternal blood in early pregnancy

1998 ◽  
Vol 274 (5) ◽  
pp. R1492-R1495 ◽  
Author(s):  
Stuart Ward ◽  
Eric Jauniaux ◽  
Claire Shannon ◽  
Charles Rodeck ◽  
Robert Boyd ◽  
...  
Keyword(s):  
Electrical Potential ◽  
Extracellular Fluid ◽  
First Trimester ◽  
Maternal Blood ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Amniotic Cavity ◽  
Normal Human ◽  
The Mean ◽  
Forearm Vein

The forces that drive transfer of solutes between maternal blood and embryo in early human pregnancy are poorly understood. The aim of this study was to determine whether there is an electrical potential difference (PD) between maternal blood and the exocelomic cavity and between maternal blood and the amniotic cavity in the normal human conceptus at or before 10 wk of pregnancy. We measured PD between a saline-filled catheter in a forearm vein of women undergoing termination of pregnancy for psychological reasons in the first trimester and a second saline-filled catheter in the exocelomic cavity or amniotic cavity of their conceptus. The mean (±SE) maternal blood/exocelomic cavity PD in eight women was 8.7 ± 1.0 mV and the mean maternal blood/amniotic cavity PD in four of the women was 6.7 ± 1.3 mV, embryo side negative for both sets of measurement. These data show that there is a PD between maternal and embryonic extracellular fluid in the first trimester that will directly influence exchange of ions between the two compartments.

Cl- secretion by cultured shark rectal gland cells. II. Effects of forskolin on cellular electrophysiology

1991 ◽  
Vol 260 (4) ◽  
pp. C824-C831 ◽  
Author(s):  
W. M. Moran ◽  
J. D. Valentich
Keyword(s):  
Apical Membrane ◽  
Basolateral Membrane ◽  
Electrical Potential ◽  
Ringer Solution ◽  
Rectal Gland ◽  
Electrical Potential Difference ◽  
Electrophysiological Properties ◽  
Shark Rectal Gland ◽  
Membrane Electrical Potential ◽  
Cl Conductance

Employing microelectrode techniques we have assessed the cellular electrophysiological properties of shark rectal gland (SRG) cells in primary culture. In the absence of secretagogues a 10-fold reduction in the Cl- concentration of the apical superfusate shark Ringer solution had little effect on either apical membrane electrical potential difference (Va) or fractional resistance (fRa), indicating little, if any, apical membrane Cl- conductance. Superfusing the basolateral surface with high-K+ shark Ringer solution (K+ increased 10-fold) depolarized the basolateral membrane electrical potential difference (Vb) by 43 mV, indicating that this barrier is largely K+ conductive. In addition, basolateral Ba2+ (5 mM) depolarized Vb by 12 mV and reduced fRa from 0.92 to 0.58, results consistent with a K(+)-conductive basolateral membrane in unstimulated SRG cells. Basolateral forskolin (10(-6) M) depolarized Va by 25 mV and caused a dramatic reduction in fRa from 0.97 to approximately 0.10. Under these conditions, a 10-fold decrease in apical superfusate Cl- concentration depolarized Va by 37 mV, revealing an adenosine 3',5'-cyclic monophosphate-induced apical membrane Cl- conductance. The time course of the forskolin-induced changes in Va and Vb suggests that the basolateral membrane K+ conductance increased and maintained the driving force for apical Cl- exit, as in other Cl(-)-secreting epithelia. These electrophysiological properties compare favorably with those of the perfused SRG tubule and indicate that SRG primary cultures are a suitable model for Cl(-)-secreting epithelia.

Changes in electrical potential difference of rectal mucosa and of gallbladder bile constituents of dogs fed chenodeoxycholic acid

1986 ◽  
Vol 64 (8) ◽  
pp. 1115-1118
Author(s):  
J. Patrick Shoenut
Keyword(s):  
Chenodeoxycholic Acid ◽  
Dose Group ◽  
Low Dose ◽  
Electrical Potential ◽  
Rectal Mucosa ◽  
Gallbladder Bile ◽  
Potential Difference ◽  
Control Group ◽  
Electrical Potential Difference ◽  
Dissolution Studies

Eighteen dogs were studied for 54 days. Rectal mucosal electrical potential difference (PD), gallbladder bile acids, cholesterol, and phospholipids were measured. It was shown that feeding chenodeoxycholic acid (CDCA) for 24 days in dosages of 15, 30, and 60 mg/kg of body weight, all depressed PD equally but significantly (P < 0.05) in three groups of dogs compared with a control group. This depression was reversible 24 days after CDCA ingestion ceased in the two highest dosages. The low dose group was sacrificed after 24 days of CDCA feeding and the gallbladder bile was analyzed. CDCA and cholesterol were each significantly (P < 0.05) elevated over control values in the gallbladder bile of these dogs. Phospholipids were not significantly changed. The PD, a reflection of Na+–K+ ATPase activity, may be a useful indicator in maximizing dosages of CDCA in gallstone dissolution studies.

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