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At least 217 records · Page 12Linked to original sources
PubMed1981

Na+-dependent co-transport of alpha-methyl D-glucoside across the mucosal border of rabbit descending colon.

(1) The uptake and bidirectional fluxes of 1-alpha-methyl D-glucoside were studied in isolated rabbit colonic mucosa. (2) The uptake of alpha-methyl D-glucoside was linear over the first 30 min and reached maximum after 1 h; was a saturable function of sugar concentration and was Na+-dependent. (3) An increase in sugar uptake across the mucosal border and net transepithelial sugar flux across sheets of colon was observed in the presence of 10(-4) M amiloride. (4) Phlorizin (10(-4) M) inhibited sugar uptake into the tissue water and abolished net sugar flux. Amiloride-stimulated sugar uptake was also abolished by 10(-4) M phlorizin. (5) Ouabain (10(-4) M) prevented the effect of amiloride on sugar uptake and inhibited sugar uptake into the tissue. (6) These results corroborate the findings of Henriques de Jesus et al. (Henriques de Jesus, C., Da Gracia Emilio, M. and Santos, M.A. Gastroenterol. Clin. Biol. 3, 172-173) who found a sugar-dependent increase in short-circuit current in colonic mucosa exposed to amiloride.

Amiloride↗
PubMed1979

The role of calcium and cyclic AMP in the contractile action of angiotensin II upon rat descending colon.

The effect of procedures which affect calcium availability and tissue levels of cyclic AMP were investigated upon the contractions of rat colon to angiotensin II, PGE2 and KCl. Calcium free Tyrode containing EDTA (25 microM) reduced the response to angiotensin more than to PGE2 and KCl. An increase in calcium concentration to 3.6 mM potentiated responses to angiotensin and KCl. A further increase to either 7.2 mM or 10.8 mM still potentiated responses to angiotensin but those to KCl wre reduced. SKF 525A (2.6 x 10(-5) M) and verapamil (3.5 x 10(-6) M) inhibited the responses to KCl but the responses to PGE2 and angiotensin were less affected. Isoprenaline, Theophylline and dibutyryl cyclic AMP preferentially reduced the responses to angiotensin and PGE2. It is suggested that part of the response to angiotensin involves an influx of calcium, independent of depolarisation.

Angiotensin II↗
PubMed1983

Adenocarcinoma of the retroperitoneal ascending and descending colon: sites of initial dissemination and clinical patterns of recurrence following surgery alone.

One hundred twenty-seven patients with previously untreated primary carcinomas of proximal, retroperitoneal large bowel were retrospectively analyzed. Sites of involvement in 33 patients with surgically incurable (disseminated) disease were analyzed to define patterns of initial spread. Ninety-four patients were analyzed following attempted curative resection to determine anatomical distribution of initial clinical recurrences. Thirty-one patients recurred (33%). Twenty-four of these patients (77.5%) demonstrated an initial pattern of relapse clinically confined to the abdomen and retroperitoneum. Analysis was performed to identify factors of prognostic significance. Implications for adjuvant therapy are discussed.

Adenocarcinoma↗
PubMed1989

Effects of alpha- and beta-calcitonin gene-related peptides upon ion transport in rat descending colon.

Both alpha- and beta-calcitonin gene-related peptide (CGRP) exhibit concentration-dependent dual actions upon rat colonic epithelia. At low concentrations (i.e. 0.03-10 nM) both CGRPs produce antisecretory effects that are abolished by pretreating tissues with tetrodotoxin (TTX). At higher concentrations (30-200 nM) secretory responses predominate and these effects are not abolished by TTX. It is suggested that the mediator of the antisecretory actions of CGRPs is somatostatin.

Animals↗
PubMed1988

A comparison of enterotomies through the antimesenteric band and the sacculation of the small (descending) colon of ponies.

Three pairs of longitudinal enterotomies were performed in the small colon of 10 ponies. Each pair consisted of one enterotomy through the antimesenteric band and one through the sacculation. The ponies were destroyed 96 h after surgery. The enterotomies in the two sites were compared for: speed of surgery, adhesions, bursting wall tension, neovascularisation by micro-angiography, and histological reaction. Enterotomies made through the antimesenteric band were superior because they were quicker to perform, stronger, more accurately apposed, and had less inflammation than those made through the sacculation.

Angiography↗
PubMed1986

Potassium secretion by rabbit descending colon: effects of adrenergic stimuli.

Stripped rabbit distal colonic mucosa was studied in vitro in Ussing chambers to investigate the effects of adrenergic stimuli on Na+, K+, and Cl- transport. The adrenergic stimuli epinephrine and norepinephrine decrease short-circuit current in a dose-dependent manner, with a half-maximal effect at 5 X 10(-7) M and a maximal effect between 10(-5) and 10(-4) M. The effects produced by norepinephrine and epinephrine can also be elicited by the beta 1-agonist dobutamine, but not by the beta 2-agonist terbutaline or the alpha-agonist phenylephrine. In addition, the effects of adrenergic stimulation can be inhibited by the beta-antagonist propranolol but not by the muscarinic antagonist atropine, the alpha 2-antagonist yohimbine, or tetrodotoxin. The decrease in short-circuit current elicited by adrenergic stimuli is accompanied by an increase in net K+ secretion with no change in net Cl- or Na+ transport. This increase in net K+ secretion elicited by beta-adrenergic stimulation can be inhibited by trifluoperazine but not by indomethacin. These studies suggest that K+ transport by the colon can be regulated by adrenergic agents acting via beta 1-receptors.

Alprostadil↗
PubMed1990

Hypertonic fluid absorption from rabbit descending colon in vitro.

Fluid and solute movements across rabbit distal colonic mucosa were investigated to determine the solute concentration of the absorbate and to characterize the absorption process. With isotonic mucosal and serosal bathing solutions the osmolality of the absorbate was 492 +/- 22 mosmol/kg. When the absorbate concentration was corrected for passive components of water and salt flux, the concentration of the "active" component was 1,062 +/- 206 mosmol/kg. Octanol (2 mM) caused a decrease in net solute and water absorption and in the concentration of the absorbate. Cytochalasin D (20 microM) increased the absorbate tonicity and decreased the hydraulic conductance of the active route for water movement. Correlations were made with measurements of the total crypt and crypt luminal cross-sectional areas. Ouabain, octanol, deoxycholate, and theophylline increase the cross-sectional area of the crypt lumen relative to that of the total crypt. These findings suggest that the hypertonic component of fluid absorption is via the crypts. The large osmotic pressure across the crypt wall could provide the considerable fluid tension (5 atm) required to dehydrate feces.

Animals↗