The influence of acetoacetate and butyrate on calcium influx and ATP concentrations in HT-29 cells

The effects of acetoacetate and butyrate on Ca2+ influx in HT-29 cells were unknown, Extracellular signals can be transferred to the intracellular env ironment of the cell via changes in the Ca2+-concentration. Extracellular C a2+ may enter the cell via Ca2+-channels in the plasma membrane. Physiologi cal processes occurring within the cell are dependent on Ca2+-concentration , including enzyme activity. Intracellular Ca2+-concentrations were measure d using Fura-2/AM, a fluorescent intracellular Ca2+-probe. Ca2+-concentrati ons 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 Ca2+-channels were determined using the whole- cell patch-clamp technique. To validate these results for the intestinal ep ithelial model, membrane current studies were performed on HT-29 cells grow n on a polycarbonate membrane. ATP concentrations were measured, and the th eoretical effect of the inducers on PDE 4 activity was determined. It was f ound that both acetoacetate rind butyrate blocked Ca2+-influx through the L -type voltage-operated Ca2+-channels, resulting in the initial low Ca2+-con centration (p < 0.05). The blockage effect is short-lived as after a 9 day incubation period in the presence of the inducers, Ca2+-concentrations were higher than that of the HT-29 control sample (p < 0.05). ATP concentration s of the cells were decreased in the presence of the inducers (p < 0.05), w hilst it was suggested that no interaction between the catalytic site of PD E 4 and the inducers existed.