METHODIC PROBLEMS IN MICROCALORIMETRIC MEASUREMENTS OF HUMAN COLONIC MUCOSA

152 biopsies from the colon of healthy persons were incubated with sev eral nutrition mediums in a microcalorimeter. The course of the heat-f low rate was measured at 1 min interval and graphically displayed as a function of time. For evaluation of the results, the maximum (P-max), the mean values (P), and the area under the curve as a measure of the total released energy (E-tot) of the power-time curves were determine d. The mean enthalpy change of all samples over time was 3.9 mu W per sample. Depending on incubation conditions, mean values ranged between 2.5 and 7.1 mu W, maximal values between 3.5 and 13.3 mu W. The areas under the curve varied between 6.2 and 18.3 mJ. Our results also show ed that bacterial growth can influence measured enthalpy changes if an tibiotics are not present. Under identical incubation conditions, stee l ampoules were better than glass ampoules with respect to methodic ar tifacts. We conclude that microcalorimetric investigations on bioptic material from colonic epithelium are possible. Interestingly, our meas ured enthalpy changes were lower than those expected from the oxygen c onsumption rates and other metabolic processes. The reason is yet to b e explored. (C) 1997 Elsevier Science B.V.