The influence of acetoacetate and butyrate on calcium influx and ATP concentrations in HT-29 cells
Jamie, H.; Dyason, K.; Milne, P.J.; Grant, G.; Graz, C.J.
Die Pharmazie 56(4): 332-336
2001
ISSN/ISBN: 0031-7144 PMID: 11338676 Document Number: 536472
The effects of acetoacetate and butyrate on Ca(2+)-influx in HT-29 cells were unknown. Extracellular signals can be transferred to the intracellular environment of the cell via changes in the Ca(2+)-concentration. Extracellular Ca2+ may enter the cell via Ca(2+)-channels in the plasma membrane. Physiological processes occurring within the cell are dependent on Ca(2+)-concentration, including enzyme activity. Intracellular Ca(2+)-concentrations were measured using Fura-2/AM, a fluorescent intracellular Ca(2+)-probe. Ca(2+)-concentrations were measured immediately on application of the inducers to the cells, as well as after a 9 day incubation period. The effect of these inducers on the L-type voltage-operated Ca(2+)-channels were determined using the whole-cell patch-clamp technique. To validate these results for the intestinal epithelial model, membrane current studies were performed on HT-29 cells grown on a polycarbonate membrane. ATP concentrations were measured, and the theoretical effect of the inducers on PDE 4 activity was determined. It was found that both acetoacetate and butyrate blocked Ca(2+)-influx through the L-type voltage-operated Ca(2+)-channels, resulting in the initial low Ca(2+)-concentration (p < 0.05). The blockage effect is short-lived as after a 9 day incubation period in the presence of the inducers, Ca(2+)-concentrations were higher than that of the HT-29 control sample (p < 0.05). ATP concentrations of the cells were decreased in the presence of the inducers (p < 0.05), whilst it was suggested that no interaction between the catalytic site of PDE 4 and the inducers existed.