Propionate alters ion transport by rabbit distal colon
The primary anions of the colon are short-chain fatty acids (SCFA) produced by intestinal microorganisms from endogenous secretions and dietary fiber. The effects of the SCFA propionate on ion transport by the epithelium of rabbit distal colon were studied on tissues stripped of underlying musculature and mounted in Ussing chambers. When tissues were bathed with NaCl Ringer's solutions at 37/sup 0/C (5% CO/sub 2/-21mM HCO/sub 3/, pH 7.4) replacement of 33mM Cl/sup -/ in both tissue baths by propionate reduced short-circuit current (Isc) from 86 to 35 ..mu..A/cm/sup 2/ and increased transepithelial conductance (G/sub t/) from 3.6 to 5.6mS/cm/sup 2/. Unidirectional /sup 14/C-propionate flux measurements revealed that this ion was secreted at a rate of 0.5..mu..Eq/cm/sup 2/hr. Intracellular measurements with potential and pH sensitive microelectrodes showed that propionate reduced intracellular pH (PH/sub i/) from 6.84 to 6.68 (P < 0.02), depolarized the apical membrane potential (phi/sub a/) by 4mV (P < 0.02) and decreased the membrane fractional resistance (f/sub R/) from .78 to .71 (P < 0.001). Addition of 0.1mM amiloride to the mucosal bath reversed Isc to -18..mu..A/cm/sup 2/, decreased G/sub t/ to 5.3mS/cm/sup 2/, hyperpolarized phi/sub a/ by 5mV (P < 0.05) and increased f/sub R/ to 0.85 (P < 0.001). Amiloride had no effect on pH/sub i/. These results show that propionate can be secreted by rabbit distal colon and that exposure to this SCFA causes cell acidification and electrophysiological changes consistent with H/sup +/ secretion.
- Research Organization:
- SUNY, Buffalo
- OSTI ID:
- 5450974
- Report Number(s):
- CONF-8604222-; TRN: 86-028358
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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EPITHELIUM
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PROPIONIC ACID
BIOLOGICAL EFFECTS
SECRETION
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
ION EXCHANGE
LARGE INTESTINE
MEMBRANE TRANSPORT
RABBITS
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ANIMAL TISSUES
ANIMALS
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MAMMALS
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MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PHYSIOLOGY
TISSUES
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550201* - Biochemistry- Tracer Techniques