Electrical effects of potassium and bicarbonate on proximal tubule cells ofNecturus

Matsumura, Yutaka; Cohen, Brian J.; Guggino, William B.; Giebisch, Gerhard

doi:10.1007/bf01872118

Cited by 46 publications

(25 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the previous studies with pH microelectrodes on amphibian kidneys, several HCO3 -transport mechanisms have been reported to exist in the peritubular membrane. These mechanisms are listed as follows: 1) electrogenic Na +-HCO3 -cotransport system (BORON and BOULPAEP, 1983); 2) inward Na + -dependent HCO3-/Clexchange system M. FUJIMOTO, N. HAGIWARA, T. KUBOTA, and K. KOTERA (GUGGINO et al, 1983); 3) simple current carrying HCO3 -exit (MATSUMURA et al, 1984); 4) electro-neutral HCO3 -/Cl -exchange system (FUJIM0T0 and M0RIM0T0, 1986). If these HC03 -transport mechanisms were inhibited by db-cAMP, then intracellular alkalinization might ensue.…”

Section: Discussionmentioning

confidence: 99%

The effect of cAMP on ion transport in the proximal tubular cells in bullfrog kidney.

et al. 1988

View full text Add to dashboard Cite

Using a direct cellular micropuncture technique with doublebarreled ion-selective microelectrodes, we investigated the effect of dibutyryl-cyclic AMP (db-cAMP) on the membrane potential and the transport of Na +, K +, and H + in doubly-perfused bullfrog proximal tubules. The peritubular membrane potential difference (EM) and the intracellular K+, Na+ activities ((K);, (Na);) or intracellular and luminal pH were monitored continuously after peritubular administration of dbcAMP (10-3-10-4 M). Results: 1) db-cAMP hyperpolarized the EM by 8.0 mV with an increase of (K); by 4.8 mEq/l; 2) the peritubular administration of high K + (13.5 and 50 mM) solutions depolarized the EM by 11.5 and 41.5 mV, respectively. The high K + perfusate with db-cAMP produced a depolarization to the same level as that in simple high K + perfusion without db-cAMP; 3) db-cAMP transiently blocked the luminal acidification concomitantly with a cellular alkalinization by about 0.1 pH; and 4) db-cAMP caused a decrease of (Na); by 5.0 mEq/l. Conclusions: 1) cAMP causes an increase of K+ permeability in the peritubular membrane; 2) cAMP induces a cytosol alkalosis by enhancing incorporation of H+ into the subcellular vesicles, thus favoring the activation of Na+/K+ pump; and 3) cAMP, in effect, suppresses the Na+/H+ exchange mechanism in the luminal membrane and transiently blocks the proximal urinary acidification.

show abstract

Section: Discussionmentioning

confidence: 99%

The effect of cAMP on ion transport in the proximal tubular cells in bullfrog kidney.

et al. 1988

View full text Add to dashboard Cite

show abstract

“…The thermodynamic approach we used here to conclude that the Na+-HCO5 cotransporter has a stoichiometry of 3HCO-: 1Na+ under these conditions is similar to that used by Lopes et al (11), except that they were obliged to calculate the stoichiometry by using values of (Na+)i measured by other authors (21,22), whereas we were able to measure (Na+)i and (HCO )i in the same preparation.…”

Section: Discussionmentioning

confidence: 92%

Change of apparent stoichiometry of proximal-tubule Na(+)-HCO3- cotransport upon experimental reversal of its orientation.

Planelles

Thomas

Anagnostopoulos

1993

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Electrogenic cotransport of Na+ with HCO3 has been reported in numerous tissues. It has always been shown with a net transfer of negative charge, but in some situations achieves net outward transport of both species with a stoichiometry of at least three HCO-ions per Na+ ion (3:1), and in other situations achieves net inward transport of both species and has a stoichiometry of at most two HCO-ions per Na+ ion (2:1). This suggests either that there may be more than one protein responsible for Na+-HCO-cotransport in different tissues or that if there is a single protein, its stoichiometry may differ depending on the orientation of net transport. The present study, using conventional or double-barreled ionselective microelectrodes to follow basolateral membrane potential and intracellular pH or Na+ activity in Necturus proximal convoluted tubule in vivo, shows that the orientation of the basolateral Na+-HCO-cotransporter can be reversed upon switching from a perfusate simulating normal acid-base conditions to one that imposes peritubular isohydric hypercapnia. Moreover, accompanying the reversal oforientation is a change of apparent stoichiometry from 3:1 to 2:1. Given that the observed change of orientation and accompanying change of apparent stoichiometry occur within seconds and in the same preparation, these results suggest that a single transport protein is responsible for both types of behavior.

show abstract

“…When the bicarbonate conductance is reduced, the membrane potential tends to hyperpolarize. The same degree of hyperpolarization is also generated when K+ conductance is increased (MATSUMURA et al, 1984a). Probably, the balance of the above two conductances determine both the membrane potential and cell pH.…”

Section: Discussionmentioning

confidence: 99%

“…The key factor in the relationship between H+ secretion and peritubular membrane potential would be an intracellular sodium concentration, which is regulated by the activities of Nat, K~-ATPase. On the other hand, electrical diffusion of HCO3-across the basolateral membrane (FROEMTER and SATO, 1976;MATSUMURA et al, 1984a;MORIMOTO and FUJIMOTO, 1984;BURCKHARDT et al, 1984;YOSHITOMI and FROEMTER, 1984) may act as a consumer of the electrochemical driving forces for Na+ built up by the Nat, K+-ATPase activity. An increase of W secretion into the lumen may induce an accumulation of bicarbonate within the cell.…”

Section: Discussionmentioning

confidence: 99%

“…Peritubular HC03-conductive pathway was observed by MATSUMURA et al (1984a) in a doubly-perfused Necturus kidney and in vivo rat proximal tubule (YosHITOMI and FROEMTER, 1984), with neutral carrier pH microelectrodes. Moreover, BORON and BoULPAEP (1983b), and GUGGINO et al (1983), who used Thomas type pH glass microelectrodes, supported the existence of 1) Na+-H+ exchanger for H+ exit and Na+-2HC03-cotransporter for HC03-exit (BORON and BOULPAEP,1983a, b) and 2) Na+-2HC03--Cl-exchanger for Cl-exit and HC03-uptake (GUGGINO et al, 1983) across the peritubular membrane of salamander and Necturus kidneys.…”

mentioning

confidence: 95%

See 1 more Smart Citation

Regulatory mechanism of cell pH in the renal proximal tubule of bullfrog nephron.

1985

View full text Add to dashboard Cite

To examine the cellular mechanism of urinary acidification in detail, micropuncture studies were performed on the in situ bullfrog proximal tubule with nigericin-based pH microelectrodes. Pencil-type double-barreled antimony microelectrodes were also used for monitoring pHs of the tubular fluids. Luminal perfusion of 10 M cyanide caused a biphasic change in cell pH (pHi) : i.e., early acidification by 0.04 pH unit in 2 min and later alkalinization by 0.04. A profound depolarization of 30-35 mY was observed in the peritubular membrane potential (EM Pen), although the tubular fluid pH (PHTF) was elevated by 0.11 unit. Luminal substitution of 100 mM Na+ by Li+ acidified the cell by 0.06 pH unit with a depolarization of EM Peni by 8 mY and an alkalinization of pHTF by 0.10 unit. It is a fact that cellular acidification and luminal alkalinization are in good agreement with the depression of luminal H+ secretory mechanism. Perfusion of 104 M SITS from the peritubular side caued a rise in pHi by 0.04 without appreciable changes in EM Peni in the short period application. Peritubular perfusion of 10 M ouabain lowered the pHi by 0.07 with a resulting depolarization of EM Peni by 15.4 mY, meanwhile, the pHTF, while initially lowered by 0.07 unit, was elevated 4 min later by 0.12. Inhibitions of the peritubular ion transport mechanism caused some pH changes in the same direction, both in the cell interior and the tubular fluid. Further, from the ouabain experiment, it is inferred that some linkages, mediated by Na+ and H+(or HC03-), would exist between the peritubular and luminal membranes.

show abstract

Electrical effects of potassium and bicarbonate on proximal tubule cells ofNecturus

Cited by 46 publications

References 19 publications

The effect of cAMP on ion transport in the proximal tubular cells in bullfrog kidney.

The effect of cAMP on ion transport in the proximal tubular cells in bullfrog kidney.

Change of apparent stoichiometry of proximal-tubule Na(+)-HCO3- cotransport upon experimental reversal of its orientation.

Regulatory mechanism of cell pH in the renal proximal tubule of bullfrog nephron.

Contact Info

Product

Resources

About