Oxidative metabolism of rabbit ileal mucosa

Ra, Frizzell; Markscheid-Kaspi, L; Sg, Schultz

doi:10.1152/ajplegacy.1974.226.5.1142

Cited by 33 publications

(6 citation statements)

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“…Acetazolamide inhibits HCO3secretion in rat intestine in vivo (Parsons, 1956) but this effect was interpreted with caution because of the low activity of carbonic anhydrase in intestine (Kuriaki & Magee, 1964;Maren, 1967;Carter & Parson, 1971) and the apparently unrelated inhibitory effect of acetazolamide on Clabsorption. More recently Frizzell, Markscheid-Kaspi & Schultz (1974) reported that acetazolamide had no effect on the rate of HCO3production by stripped segments of rabbit ileum. In contrast the effectiveness of acetazolamide in inhibiting JHC03 in this study at concentrations low enough to avoid non-specific effects (Maren, 1977), and the presence of measurable amounts of carbonic anhydrase activity in the urodele intestinal epithelium (Fig.…”

Section: Discussionmentioning

confidence: 97%

Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions.

Imon¹,

White²

1981

The Journal of Physiology

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SUMMARY1. Isolated Amphiuma small intestine exposed on both surfaces to buffered or unbuffered media generated gradients of pH under short-circuited conditions consistent with secretion of HCO3-.2. When unbuffered mucosal medium was maintained at pH 7-4 by addition of acid, alkalinization of the mucosal medium occurred at a rate of 1-2 #tequiv/hr cm2 under short-circuit conditions (Is,) and was reduced by anoxia, acetazolamide or removal of CO2. 3. The rate of HCO3-secretion (JHCO3-) was reduced at a mucosal pH above or below 7-4 and was proportional to serosal HCO3-.4. JHCO3 was reduced in Na+-free (choline) and Cl--free (SO42-) media and after exposure to the stilbene SITS.5. The difference JHCO3 -lS was consistent with net Cl-absorption.6. The tissue resistance (Rt) was elevated upon exposure to serosal HCO3-and lowered by mucosal HCO3-.7. The intestinal mucosa exhibited carbonic anhydrase activity that was sensitive to ethoxazolamide.8. It is concluded that HCO3-secretion is active, influenced by intracellular carbonic anhydrase activity and coupled to Cl-and possibly Na+ absorption.

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Section: Discussionmentioning

confidence: 97%

Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions.

Imon¹,

White²

1981

The Journal of Physiology

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“…Gallbladders were excised, opened and rinsed free of bile in control bathing solution at 0~ Since the oxygen consumption (0o2) of rabbit ileal mucosa was greatly depressed with the serosal musculature intact (Frizzell, Markscheid-Kaspi & Schultz, 1974), the muscle layers of gallbladder were removed 4 It is assumed from Fig. 6 that the spontaneous PD of each gallbladder is reduced by 25% due to reducing the Na concentration in the bathing solutions by 50% in the absence of a transmural ion gradient.…”

Section: Oxygen Consumption Measurementsmentioning

confidence: 99%

Electrolyte transport by gallbladders of rabbit and guinea pig: Effect of amphotericin B and evidence of rheogenic Na transport

Rose

Nahrwold

1976

J. Membrain Biol.

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Ion transport and electrical properties of rabbit and guinea pig gallbladders were investigated to gain further information about the active transport mechanism that mediates fluid absorption. The intracellular and transepithelial electrical potentials were measured simultaneously using the microelectrode technique. Exposure of the mucosal surface to Amphotericin B resulted in the prompt development of a serosa-positive electrical potential difference (PD) which could not be attributed to an alteration in ion diffusion potentials across either the cell membrane or across the tight junction. Because the Amphotericin B-induced PD was immediately dependent on warm temperatures and O2, and was independent of NA and K concentration gradients across the cell membrane, it is suggested that active ion transport is directly responsible for the PD. Since the PD was abolished in the absence of Na in the bathing solutions, a rheogenic Na pump is postulated; this pump also appears to be operative in tissues not exposed to Amphotericin B. The specific tissue properties altered by Amphotericin B to produce a serosa-positive PD remain incompletely defined. The results of the present study indicate that ion transport by rabbit gallbladder in vitro is a consequence of a rheogenic active Na transport mechanism at the basolateral membranes which, in conjunction with a coupled NaC1 influx process at the mucosal border, ultimately results in absorption of NaC1 and water.

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“…As indicated in Table I, ouabain (10-4 M) decreased I,, nearly to zero but had no effect on J" or on o 0 J. Tissue conductance decreased significantly below control levels but the decrease in oJ0S"m. was not statistically significant. Finally, in view of the observation that theophylline stimulates ionic secretory processes in intestine (7,18,5), the effect of this agent was studied with results shown in the last row of Table I. Theophylline (10-2 M) increased J:, significantly above the control level (P < 0.01) and significantly decreased both tissue conductance and Jdm.…”

Section: Properties Of J~cmmentioning

confidence: 99%

Characteristics of Sodium Flux from Serosa to Mucosa in Rabbit Ileum

Desjeux

Tai

Curran

1974

The Journal of General Physiology

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Sodium flux from serosa to mucosa, JN, in rabbit ileum in vitro has been studied as a function of applied electrical potential at equal sodium concentrations in the bathing solutions. The results indicate that J involves two pathways, a diffusional flux through a paracellular shunt pathway and a flux that is independent of applied potential and presumably involves a transcellular pathway. The latter pathway comprises approximately 25 % of J in Ringer's solution containing 10 mM glucose and 25 mM bicarbonate. It is stimulated significantly by theophylline unaffected by removal of glucose or addition of ouabain but is reduced to negligible values by anoxia, dinitrophenol, and replacement of all chloride and bicarbonate by isethionate. Thus this component of J:L has a number of characteristics consistent with involvement in a specific secretory process mediating an electrically neutral secretory transport of sodium plus anion from serosa to mucosa. In addition to stimulating this process, theophylline significantly reduced the permeability of the paracellular shunt pathway to sodium.Recent studies on ion transport across rabbit ileum have raised certain questions about mechanisms involved in movement of ions from the serosal to the mucosal side of the tissue. For example, Frizzell and Schultz (1) have suggested that nearly all of the Na flux from serosa to mucosa across in vitro preparations of rabbit ileum occurs via the intercellular shunt pathway they have described (see also Rose and Schultz [2]). On the other hand, Powell et al. have proposed that there may be an active secretory process for Na in guinea pig ileum (3) and rabbit ileum (4, 5) that accounts for a part of the observed serosal-to-mucosal flux and that this process may be stimulated by cholera toxin (6) and theophylline (5). Such a process might be expected to involve transcellular movement of Na and would not be consistent with purely passive Na movement from serosa to mucosa via a shunt pathway. The situation is further complicated by the suggestion of Field et al. (7,8) that the THE JOURNAL OF GENERAL PHYSIOLOGY

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Oxidative metabolism of rabbit ileal mucosa

Cited by 33 publications

References 0 publications

Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions.

Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions.

Electrolyte transport by gallbladders of rabbit and guinea pig: Effect of amphotericin B and evidence of rheogenic Na transport

Characteristics of Sodium Flux from Serosa to Mucosa in Rabbit Ileum

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