title: Effects on fluid and Na+ flux of varying luminal hydraulic resistance in rat colon in vivo.
abstract: 1. A new method of measuring fluid and ionic movements and the dehydrating power of the colon in vivo is described. A range of agarose gel cylinders, with calibrated hydraulic conductivities (Lp), were inserted into the lumen of the descending colon of anaesthetized rats. Fluxes of fluid, Na+ and K+ out of the gels were measured over a period of 60-110 min. 2. Fluid absorption by the colon from 2.5% agarose gels was not slower than from solution without gel. Fluid absorption was inhibited by 66% when the agarose concentration was raised to 10%. In contrast 2.5% agarose gels caused a 73% (P < 0.001) reduction in water flow from rat ileum. 3. Increasing gel concentration to 10% or above caused the absorbate from the gels to become hypertonic (P < 0.001). 4. The measured suction pressure applied by the colonic hypertonic absorbate to the gels increased from 44 +/- 2.3 cmH2O (n = 23) with 2.5% agarose gels to 6713 +/- 960 cmH2O (n = 13) with 15% (P < 0.001). 5. Deoxycholate (2 mM) produced a decrease in fluid and Na+ absorption and reduced the suction pressure and power exerted by the colon.
authors.affiliation: King's College London, Division of Biological Sciences, Strand.
authors.forename: P S
authors.initials: PS
authors.lastname: Zammit
authors.forename: M
authors.initials: M
authors.lastname: Mendizabal
authors.forename: R J
authors.initials: RJ
authors.lastname: Naftalin
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000378:metabolism*; D003106:Colon / Q000378:metabolism*; D003840:Deoxycholic Acid / Q000494:pharmacology; D004573:Electrolytes / Q000378:metabolism; D005782:Gels; D007408:Intestinal Absorption; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar; D012685:Sepharose; D012964:Sodium / Q000378:metabolism*; D013396:Suction; D013997:Time Factors
chemical_list: D004573:Electrolytes; D005782:Gels; D003840:Deoxycholic Acid; D012685:Sepharose; D012964:Sodium; D011188:Potassium