Propionate activates multiple ion transport mechanisms in the HT29-18-C1 human colon cell line.
THE AMERICAN JOURNAL OF PHYSIOLOGY 1993;
265:G564-71. [PMID:
8214077 DOI:
10.1152/ajpgi.1993.265.3.g564]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Short-chain fatty acids (SCFAs) are the major solutes and the major anions in the colonic lumen. We studied the response of suspended HT29-18-C1 cells (an epithelial cell line derived from a human colon carcinoma) to SCFA exposure. Cellular response was evaluated by measurement of cell volume (Coulter counter), intracellular pH [pHi; measured fluorometrically with 2',7'-bis(2-carboxyethyl)-5-(6)-carboxyfluorescein (BCECF)], and intracellular Na+, K+, and Cl- content (flame photometry and chloride titrator). Exposure to 130 mM propionate in isosmotic medium causes a rapid decrease in pHi and activates pHi recovery via amiloride-sensitive Na-H exchange. In the presence of propionate, Na-H exchange also causes cell swelling to a peak volume 11% above control cells and causes a 2.8-fold increase in intracellular Na+ content. After peak swelling, a regulatory-volume decrease (RVD) significantly reduced volume and intracellular Na+ returned to baseline. Other SCFAs (acetate, butyrate, and valerate) also elicit swelling and RVD. Activation of the Na(+)-K(+)-adenosinetriphosphatase (ATPase) is required to return Na+ to normal levels and to indirectly provide ion gradients required for propionate-induced RVD, but Na(+)-K(+)-ATPase activity does not directly mediate RVD. When 1 mM 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) is added in the presence of propionate, RVD was inhibited and cell Na+ content increased. Cl- depletion inhibited propionate-induced RVD and diminished the effect of SITS.
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