Segmental differences in electrical properties and Na-transport of rabbit caecum, proximal and distal colon in vitro

Clauss, Wolfgang; Schäfer, Horst; Horch, Ingrid; Hörnicke, H.

doi:10.1007/bf00583600

Cited by 66 publications

(26 citation statements)

References 18 publications

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“…Baseline I SC in DC 4 was significantly higher than that observed in DC 1 , although the transepithelial resistance has no significant difference between DC 1 and DC 4 which was consistent with the results of previous reports. 12,13) It has been reported that a spontaneous production of neuronally acting prostaglandins in rat distal colon. 6) Park et al found that suppression of prostaglandin biosynthesis decreased the secretory responses to the CCh and forskolin in human rectum and increased the sensitivity of the tissues to CCh and forskolin in human ascending colon, and they considered that the clear segmental heterogeneity with regard to electrogenic secretion between ascending colon and rectum can be explained by differences in the action of endogenous prostaglandin.…”

Section: Discussionmentioning

confidence: 99%

Segmental Heterogeneity of Epithelial Ion Transport Induced by Stimulants in Rat Distal Colon

Yang

Xue

Guo

et al. 2006

Biological & Pharmaceutical Bulletin

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Mammalian colon plays an important role in electrolytes and water balance, and exhibits significant segmental heterogeneity along its longitudinal axis.1) The mucosa of the colonic inner surface is a typical electrolyte-transporting epithelium, which is able to move large quantities of ion and water from the mucosal side to the blood side and vice versa.2) It has been reported that the net absorption of water, sodium and chloride, 3) as well as amiloride-sensitive shortcircuit current (I SC ) 4) was dominant in distal colon than that in proximal colon, and the same activators could induce various responses in the different segments of colon. 1,6) Nobles et al. reported that the distal segments of the rat colon were more sensitive to carbachol (CCh), a Ca 2ϩ pathway activator, as well as forskolin, a cAMP pathway activator 5) which provide the evidences for the segmental specificity with regard to the intracellular signaling pathway responsible for the activation of secretion. Using PCR technique, Greig et al. found that the expression of ENaC (epithelial Na ϩ channel) was different between the rat proximal colon and distal colon. 7)Recently, the segmental heterogeneity of endogenous prostaglandin was also reported to contribute to the differences in human colon secretory responses. 1)Ion transport in gastrointestinal tract is under the control of neurotransmitters and hormones.8) The distribution of various kinds of receptors is also different in both segments of distal and proximal colon. Norepinephrine produced segment-specific effects on ion transport via different kind of receptors. 9) However, most studies were undertaken to investigate the differences between the proximal and distal colon 3,10) or between the colon and rectum.11) During our study, we found that even within the rat distal colon, the responses difference to stimulants also existed in the different segments. But there are a limited number of studies performed to compare the distinction. In the present study, the segmental heterogeneity of epithelial responses to different stimulants and its possible mechanism were investigated in rat distal colon. MATERIALS AND METHODS SolutionsThe Ussing chamber experiments were carried out in Krebs-Henseleit solution (K-HS) contained (in mM): NaCl, 117; KCl, 4.7; MgCl 2 , 1.2; KH 2 PO 4 , 1.2; NaHCO 3 , 24.8; CaCl 2 , 2.5; glucose, 11.1. The solution was bubbled with 95% O 2 -5% CO 2 to maintain the pH of the solution at 7.4; temperature at 37°C. Tissue Preparation Animal protocols followed guidelines established by the NIH and were approved by Animal Care and Use Committee, Capital University of Medical Sciences. Adult male Sprague-Dawley rats (Laboratory Animal Services Center, Capital University of Medical Sciences) ranging in weight from 200 to 300 g had free access to standard rodent laboratory food and water until the day of the experiments. The animals were killed by cervical dislocation. The distal colon was removed and defined as the ca. 7 cmlong segment proximal to the lymph node (typically situat...

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Section: Discussionmentioning

confidence: 99%

Segmental Heterogeneity of Epithelial Ion Transport Induced by Stimulants in Rat Distal Colon

Yang

Xue

Guo

et al. 2006

Biological & Pharmaceutical Bulletin

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“…Limited studies have suggested that the Received for publication 11 February 1987 and in revised form 26 October 1987. cecum absorbs Na efficiently (4,6). In the present study, we characterize in detail the ion transport characteristics of rabbit cecum in vitro.…”

Section: Introductionmentioning

confidence: 92%

“…Recent studies from our laboratory and others have established that there are important differences between the proximal and distal colon (1)(2)(3)(4). Additionally, there now appear to be differences within the rabbit proximal colon between the segment immediately distal to the cecum (the triple haustrated segment) and the region 10 cm beyond the cecum (the single haustrated segment) (4,5).…”

Section: Introductionmentioning

confidence: 92%

Electrogenic sodium absorption in rabbit cecum in vitro.

Sellin

Oyarzabal²,

Cragoe³

1988

J. Clin. Invest.

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Regional variations in the ion transport properties of the colon may have significant physiological and pathophysiological implications. However Thus, cecum exhibits a distinct type of electrogenic Na electrogenic Na absorption which is partially dependent on the presence of Cl and HCO3, not blocked by amiloride but by phenamil. Because of its large surface area and its novel mechanism of electrogenic Na transport, the cecum exerts an important regulatory role in colonic fluid and electrolyte balance.

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“…In proximal colon, ileum, and jejunum, the major increase in sodium absorption and short-circuit current produced by glucocorticoids is amiloride resistant, a finding uncharacteristic for an aldosterone-induced response (2,8,36,49). In distal colon, amiloride-resistant transport may be induced with low doses or concentrations ofdexamethasone and amiloride-inhibitable transport induced at doses ofdexamethasone greater than the 10 nmol dose used in this study (2,3,5,7,8,17,18).…”

Section: Discussionmentioning

confidence: 71%

“…The proximal colon of intact rats is characterized by a low transmural PD, -3.4±0.2 mV (Fig. 1), which may not be generated by active sodium absorption (15,19,31,(34)(35)(36). However, it does decrease significantly with adrenalectomy.…”

Section: Resultsmentioning

confidence: 99%

Regulation of cation transport by low doses of glucocorticoids in in vivo adrenalectomized rat colon.

Bastl¹

1987

J. Clin. Invest.

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A dose response curve for glucocorticoid-induced proximal and distal colonic cation transport in vivo was established in adrenalectomized rats. All doses (0.5-50 nmol/100 g body wt) stimulated sodium absorption. Distal sodium absorption did not saturate at dexamethasone levels that saturate the glucocorticoid receptor but also bind to > 35% of aldosterone receptors. Saturation of the pure glucocorticoid response occurred in both segments with RU26988, a synthetic glucocorticoid that does not occupy aldosterone receptors. Maximum velocities for pure glucocorticoid-induced sodium absorption were 15 and 16 teq/min per g dry tissue, and Michaelis constants (K.) were 4.2 and 4.6 X 10-' mol/liter for proximal and distal colon. Ks are similar to the dissociation constant for the colonic glucocorticoid receptor and too low for significant aldosterone receptor occupancy. Dexamethasone increased sodium absorption significantly within 30 min of injection, suggesting the response is not dependent on new protein synthesis. Similar time and dose responses in proximal and distal colon suggest glucocorticoids stimulate the same pathway in both segments.

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Segmental differences in electrical properties and Na-transport of rabbit caecum, proximal and distal colon in vitro

Cited by 66 publications

References 18 publications

Segmental Heterogeneity of Epithelial Ion Transport Induced by Stimulants in Rat Distal Colon

Segmental Heterogeneity of Epithelial Ion Transport Induced by Stimulants in Rat Distal Colon

Electrogenic sodium absorption in rabbit cecum in vitro.

Regulation of cation transport by low doses of glucocorticoids in in vivo adrenalectomized rat colon.

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