scholarly journals Effect of acid-base status in vivo on Bicarbonate transport by rabbit renal tubules in vitro.

1981 ◽  
Vol 31 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Yasuhiko IINO ◽  
Maurice B. BURG
Keyword(s):  
Bicarbonate Transport ◽  
Renal Tubules ◽  
Acid Base ◽  
Acid Base Status

Cellular actions of cAMP on HCO3(-)-secreting cells of rabbit CCD: dependence on in vivo acid-base status

1994 ◽  
Vol 266 (4) ◽  
pp. F528-F535 ◽  
Author(s):  
C. Emmons ◽  
J. B. Stokes
Keyword(s):  
Anion Exchanger ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Disulfonic Acid ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Acid Base Status

HCO3- secretion by cortical collecting duct (CCD) occurs via beta-intercalated cells. In vitro CCD HCO3- secretion is modulated by both the in vivo acid-base status of the animal and by adenosine 3',5'-cyclic monophosphate (cAMP). To investigate the mechanism of cAMP-induced HCO3- secretion, we measured intracellular pH (pHi) of individual beta-intercalated cells of CCDs dissected from alkali-loaded rabbits perfused in vitro. beta-Intercalated cells were identified by demonstrating the presence of an apical anion exchanger (cell alkalinization in response to removal of lumen Cl-). After 180 min of perfusion to permit decrease of endogenous cAMP, acute addition of 0.1 mM 8-bromo-cAMP or 1 microM isoproterenol to the bath caused a transient cellular alkalinization (> 0.20 pH units). In the symmetrical absence of either Na+, HCO3-, or Cl-, cAMP produced no change in pHi. Basolateral dihydrogen 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) for 15 min before cAMP addition also prevented this alkalinization. In contrast to the response of cells from alkali-loaded rabbits, addition of basolateral cAMP to CCDs dissected from normal rabbits resulted in an acidification of beta-intercalated cells (approximately 0.20 pH units). The present studies demonstrate the importance of the in vivo acid-base status of the animal in the regulation of CCD HCO3- secretion by beta-intercalated cells. The results identify the possible existence of a previously unrecognized Na(+)-dependent Cl-/HCO3- exchanger on the basolateral membrane of beta-intercalated cells in alkali-loaded rabbits.

scholarly journals Temperature Effects on Haemolymph Acid-Base Status In Vivo and In Vitro in the Two-Striped Grasshopper Melanoplus Bivittatus

1988 ◽  
Vol 140 (1) ◽  
pp. 421-435 ◽  
Author(s):  
JON M. HARRISON
Keyword(s):  
Body Temperature ◽  
Carbonic Acid ◽  
Temperature Shift ◽  
Effect Of Temperature ◽  
Locomotory Activity ◽  
Acid Base ◽  
Protein Dissociation ◽  
Acid Base Status

In this study, I examine the effect of temperature on haemolymph acid-base status in vivo and in vitro in the two-striped grasshopper Melanoplus bivittatus. Melanoplus bivittatus experience wide (up to 40 °C) diurnal body temperature fluctuations in the field, but maintain body temperature relatively constant during sunny days by behavioural thermoregulation. Haemolymph pH was statistically constant (7.12) between 10 and 25°C, but decreased by −0.017 units °C− from 25 to 40°C. Relative alkalinity and fractional protein dissociation were conserved only at body temperatures at which feeding and locomotory activity occur, above 20°C. Haemolymph total CO2 (Ctot) increased from 10 to 20°C and decreased from 20 to 40°C. Haemolymph Pco2 increased from 10 to 20°C and was statistically constant between 20 and 40°C. Carbonic acid pKapp in haemolymph was 6.122 at 35°C, and decreased with temperature by −0.0081 units°C−1. Haemolymph buffer value averaged −35mequivl−1pHunit−1. Haemolymph pH changes with temperature were small (less than −0.004 units°C−1) in vitro at constant Pco2. Therefore, passive physicochemical effects cannot account for the pattern of acid-base regulation in vivo. The temperature shift from 10 to 20°C was accompanied by a net addition of 4.2-6.2 mmoll−1 of bicarbonate equivalents to the haemolymph. The temperature shift from 20 to 40°C was accompanied by a net removal of 10–14 mmoll−1 of bicarbonate equivalents from the haemolymph. Haemolymph acid-base regulation in vivo during temperature changes is dominated by active variation of bicarbonate equivalents rather than by changes in Pco2 as observed for most other air-breathers.

Stimulation of chloride transport by HCO3-CO2 in rabbit cortical collecting tubule

1986 ◽  
Vol 251 (1) ◽  
pp. F49-F56 ◽  
Author(s):  
K. Tago ◽  
V. L. Schuster ◽  
J. B. Stokes
Keyword(s):  
Chloride Transport ◽  
Acid Base ◽  
Cl Transport ◽  
Collecting Tubule ◽  
Acid Base Status ◽  
Stimulation Of ◽  
Rabbit Cortical Collecting Tubule ◽  
Cortical Collecting Tubule

We examined both the role of HCO3-CO2 in Cl transport as well as the effect of in vivo acid-base status on Cl transport by the rabbit cortical collecting tubule. The lumen-to-bath 36Cl tracer flux, expressed as the rate coefficient KCl, was measured in either HEPES-buffered (CO2-free) or HCO3-CO2-containing solutions. Amiloride was added to the perfusate to minimize the transepithelial voltage and thus the electrical driving force for Cl diffusion. Because KCl fell spontaneously with time in HCO3-CO2 solutions in the absence but not the presence of cAMP, we used cAMP throughout to avoid time-dependent changes. Acute in vitro removal of bath HCO3-CO2 reduced KCl. Acetazolamide addition in HEPES-buffered solutions also lowered KCl; KCl could be restored to control values by adding exogenous HCO3-CO2 in the presence of acetazolamide. In vivo acid-base effects on Cl transport were determined by dissecting tubules from either NaHCO3-loaded or NH4Cl-loaded rabbits. Tubules from HCO3-loaded rabbits had higher rates of Cl self exchange. Acute in vitro addition of bath HCO3-CO2 increased KCl and did so to a greater degree in tubules from HCO3-loaded rabbits. Most of this effect of HCO3-CO2 addition on KCl could not be accounted for by Cl-HCO3 exchange; rather, it appeared due to stimulation of Cl self exchange. The data are consistent with 36Cl transport occurring via Cl-HCO3 exchange as well as Cl self exchange. Both processes are acutely stimulated by HCO3 and/or Co2, and both are chronically regulated by in vivo acid-base status.

The Effect of Salt Adaptation and Amiloride on the In Vivo Acid-Base Status of the Euryhaline Toad Bufo Viridis

1981 ◽  
Vol 93 (1) ◽  
pp. 93-99
Author(s):  
U. KATZ
Keyword(s):  
Tap Water ◽  
Salt Adaptation ◽  
Acid Base ◽  
Bufo Viridis ◽  
Acid Base Status ◽  
Simultaneous Decrease ◽  
Toad Bufo

1. The acid-base status of the blood of the toad Bufo viridis was studied during adaptation to high salinity and in tap water containing amiloride. 2. Both salt adaptation and immersion for 2-3 days in 5 x10−4 M amiloride in tap water resulted in a decrease in blood pH (from 7.720 ± 0.026 in tap water to 7.456±0.051 in 500 mOsm NaCl-adapted toads; mean ± S.E.), and a simultaneous decrease in the concentration of HCO3- (from 17.8 ±1.4 in tap water to 9.5±1.2 in salt-adapted toads). 3. In vitro determination of Na+/H+ exchange across the skin showed a 1:1 relation in skins from tap-water-adapted toads; this exchange was inhibited by amiloride. H+ secretion was abolished in skins from salt-adapted toads and the uptake of sodium was reduced.

scholarly journals Damage to the gastric epithelium activates cellular bicarbonate secretion via SLC26A9 Cl−/HCO3−exchange

2010 ◽  
Vol 299 (1) ◽  
pp. G255-G264 ◽  
Author(s):  
Elise S. Demitrack ◽  
Manoocher Soleimani ◽  
Marshall H. Montrose
Keyword(s):  
Interstitial Fluid ◽  
Gastric Epithelium ◽  
Acid Base ◽  
Surface Ph ◽  
Two Photon ◽  
Acid Base Status ◽  
Genetic Deletion ◽  
Knockout Animals ◽  
Tissue Compartments

Gastric surface pH (pHo) transiently increases in response to focal epithelial damage. The sources of that increase, either from paracellular leakage of interstitial fluid or transcellular acid/base fluxes, have not been determined. Using in vivo microscopy approaches we measured pHowith Cl-NERF, tissue permeability with intravenous fluorescent-dextrans to label interstitial fluid (paracellular leakage), and gastric epithelial intracellular pH (pHi) with SNARF-5F (cellular acid/base fluxes). In response to two-photon photodamage, we found that cell-impermeant dyes entered damaged cells from luminal or tissue compartments, suggesting a possible slow transcellular, but not paracellular, route for increased permeability after damage. Regarding cytosolic acid/base status, we found that damaged cells acidified (6.63 ± 0.03) after photodamage, compared with healthy surface cells both near (7.12 ± 0.06) and far (7.07 ± 0.04) from damage ( P < 0.05). This damaged cell acidification was further attenuated with 20 μM intravenous EIPA (6.34 ± 0.05, P < 0.05) but unchanged by addition of 0.5 mM luminal H2DIDS (6.64 ± 0.08, P > 0.05). Raising luminal pH did not realkalinize damaged cells, suggesting that the mechanism of acidification is not attributable to leakiness to luminal protons. Inhibition of apical HCO3−secretion with 0.5 mM luminal H2DIDS or genetic deletion of the solute-like carrier 26A9 (SLC26A9) Cl−/HCO3−exchanger blocked the pHoincrease normally observed in control animals but did not compromise repair of damaged tissue. Addition of exogenous PGE2significantly increased pHoin wild-type, but not SLC26A9 knockout, animals, suggesting that prostaglandin-stimulated HCO3−secretion is fully mediated by SLC26A9. We conclude that cellular HCO3−secretion, likely through SLC26A9, is the dominant mechanism whereby surface pH transiently increases in response to photodamage.

Experimental Cystinuria: the Cycloleucine Model. I. Amino Acid Interactions in Renal and Intestinal Epithelia

1975 ◽  
Vol 53 (6) ◽  
pp. 1027-1036 ◽  
Author(s):  
André G. Craan ◽  
Michel Bergeron
Keyword(s):  
Amino Acids ◽  
Renal Tubules ◽  
Intestinal Epithelia ◽  
Luminal Membrane ◽  
Luminal Side ◽  
Convoluted Tubules ◽  
Dibasic Amino Acids ◽  
Everted Sacs

The injection of cycloleucine (1-aminocyclopentanecarboxylic acid (ACPC)) into rats produces a hyperexcretion of dibasic amino acids and cystine, an aberration resembling cystinuria. This may constitute a model of experimental cystinuria, and the transport of amino acids involved in this disease was studied with the techniques of everted intestinal sacs (in vitro) and microinjections into renal tubules (in vivo). In everted sacs from normal rats, there was a decrease in transfer and in accumulation of L-cystine (0.03 mM), L-lysine (0.065 mM) and L-valine (0.065 mM) when ACPC was on the mucosal (luminal) side. Dibasic amino acids such as L-ariginine and L-lysine caused a similar inhibition of the transport of L-cystine. However, when ACPC was on the serosal (antiluminal) side, a lesser effect was noted while arginine and lysine had no effect. Intestinal sacs from treated rats (ACPC, 300 mg/kg × 3 days) transferred and accumulated as much L-cystine as those from control rats. The interaction between cycloleucine and L-cystine was competitive at the luminal and non-competitive at the antiluminal side of the intestine. Cycloleucine inhibited L-lysine transport in a non-competitive fashion at either side of the intestine. L-Lysine also interacted in a non-competitive fashion with L-cystine transport at the luminal membrane. In proximal convoluted tubules, the presence of L-arginine or ACPC caused a decrease in the transport of L-cystine and L-lysine. L-Valine exerted no effect. Furthermore, L-lysine and ACPC did not impair the reabsorption of L-valine significantly.These results suggest a functional heterogeneity between luminal and antiluminal membranes of renal and intestinal epithelia and the existence, at both membranes, of different transport sites for cystine and dibasic amino acids.

Effects of acute temperature change, in vivo and in vitro, on the acid–base status of blood from yellowfin tuna (Thunnus albacares)

1992 ◽  
Vol 70 (4) ◽  
pp. 654-662 ◽  
Author(s):  
Richard W. Brill ◽  
Peter G. Bushnell ◽  
David R. Jones ◽  
Manabu Shimizu
Keyword(s):  
Ion Exchange ◽  
Exchange Rates ◽  
Temperature Change ◽  
Yellowfin Tuna ◽  
Thunnus Albacares ◽  
Skipjack Tuna ◽  
Acid Base ◽  
System Temperature

In most fishes, blood acid–base regulation following a temperature change involves active adjustments of gill ion-exchange rates which take hours or days to complete. Previous studies have shown that isolated blood from skipjack tuna, Katsuwonus pelamis, and albacore, Thunnus alalunga, had rates of pH change with temperature (in the open system) equivalent to those necessary to retain net protein charge in vivo (≈ −0.016 ΔpH∙ °C−1). It was postulated that this is due to protons leaving the hemoglobin combining with plasma bicarbonate [Formula: see text], which is removed as gaseous CO2, and that this ability evolved so that tunas need not adjust gill ion-exchange rates to regulate blood pH appropriately following ambient temperature changes. We reexamined this phenomenon using blood and separated plasma from yellowfin tuna, Thunnus albacares. Unlike previous studies, our CO2 levels (0.5 and 1.5% CO2) span those seen in yellowfin tuna arterial and venous blood. Various bicarbonate concentrations [Formula: see text] were obtained by collecting blood from fully rested as well as vigorously exercised fish. We use our in vitro data to calculate basic physiochemical parameters for yellowfin tuna blood: nonbicarbonate buffering (β), the apparent first dissociation constant of carbonic acid (pKapp), and CO2 solubility (αCO2). We also determined the effects of acute temperature change on arterial pH, [Formula: see text], and partial pressures of O2 and CO2in vivo. The pH shift of yellowfin tuna blood subjected to a closed-system temperature change did not differ from previous studies of other teleosts (≈ −0.016 ΔpH∙ °C−1). The pH shift in blood subjected to open-system temperature change was Pco2 dependent and lower than that in skipjack tuna or albacore blood in vitro, but identical with that seen in yellowfin tuna blood in vivo. However, pH adjustments in vivo were caused by changes in both [Formula: see text] and Pco2. The exact mechanisms responsible for these changes remain to be elucidated.

Loss of the NHE2 Na+/H+ exchanger has no apparent effect on diarrheal state of NHE3-deficient mice

2001 ◽  
Vol 281 (6) ◽  
pp. G1385-G1396 ◽  
Author(s):  
Clara Ledoussal ◽  
Alison L. Woo ◽  
Marian L. Miller ◽  
Gary E. Shull
Keyword(s):  
Absorptive Capacity ◽  
Apparent Effect ◽  
Acid Base ◽  
Intestinal Brush Border ◽  
Apparent Reduction ◽  
Acid Base Status ◽  
Deficient Mice ◽  
Additional Loss ◽  
Partial Compensation

The expression of NHE2 and NHE3 on intestinal-brush border membranes suggests that both Na+/H+ exchangers serve absorptive functions. Studies with knockout mice showed that the loss of NHE3, but not NHE2, causes diarrhea, demonstrating that NHE3 is the major absorptive exchanger and indicating that any remaining absorptive capacity contributed by NHE2 is not sufficient to compensate fully for the loss of NHE3. To test the hypothesis that NHE2 provides partial compensation for the diarrheal state of NHE3-deficient mice, we crossed doubly heterozygous mice carrying null mutations in the Nhe2and Nhe3 genes and analyzed the phenotypes of their offspring. The additional loss of NHE2 in NHE3-deficient mice caused no apparent reduction in viability, no further impairment of systemic acid-base status or increase in aldosterone levels, and no apparent worsening of the diarrheal state. These in vivo phenotypic correlates of the absorptive defect suggest that the NaCl, HCO[Formula: see text], and fluid absorption that is dependent on apical Na+/H+ exchange is due overwhelmingly to the activity of NHE3, with little contribution from NHE2.

Regulation of urea synthesis by acid-base balance in vivo: role of NH3 concentration

1987 ◽  
Vol 252 (2) ◽  
pp. F221-F225 ◽  
Author(s):  
S. Cheema-Dhadli ◽  
R. L. Jungas ◽  
M. L. Halperin
Keyword(s):  
Ammonium Concentration ◽  
Urea Synthesis ◽  
Carbamoyl Phosphate ◽  
Acid Base Balance ◽  
Acid Base ◽  
Fixed Rate ◽  
Rate Limiting Step ◽  
Base Balance

The purpose of this study was to clarify how changes in acid-base balance influence the rate of urea synthesis in vivo. Since ureagenesis was increased by an ammonium infusion into rats, regulation seemed to be a function of the blood ammonium concentration. The rate of urea synthesis was constant at a fixed rate of ammonium infusion and independent of the conjugate base infused, chloride or bicarbonate. The steady-state blood ammonium concentration was higher in the rats that developed metabolic acidosis. Thus it appeared that regulation was not directly mediated by this ammonium concentration per se. The rate of urea synthesis was also independent of the blood pH. Accordingly, the rate of urea synthesis was examined as a function of the plasma NH3 concentration. The rate of ureagenesis was found to be directly proportional to the plasma NH3 concentration. Assuming that plasma NH3 levels reflect those in mitochondria, the NH3 concentration yielding half-maximal rates of urea synthesis (close to 2 microM) was in the same range as Km for the rate-limiting step in ureagenesis, carbamoyl phosphate synthetase (EC 6.3.4.16). These results suggest that, at a constant ammonium concentration, the decreased rate of ureagenesis caused by a pH fall in vitro could reflect an acidosis-induced decline in the concentration of true substrate (NH3) for this pathway.

Sign in / Sign up

Export Citation Format

Share Document