Effect of sulphide on short chain acyl-CoA metabolism in rat colonocytes

It has been proposed that the diminished n-butyrate oxidation observed in ulcerative colitis may be the result of sulphide induced inhibition of short chain acyl-coenzyme A (acyl-CoA) dehydrogenase activity.

To examine the acyl-CoA ester profiles in isolated rat colonic epithelial cells treated in vitro with sodium hydrogen sulphide (NaHS).

Isolated rat colonic epithelial cell suspensions were incubated for 10 minutes in the presence of [1-14C] n-butyrate (5 mM), with and without NaHS (1.5 mM). Incubations were carried out both in the presence and the absence of exogenous CoA and ATP. Metabolic performance was assessed by 14CO2 production and by acyl-CoA ester production measured by HPLC with ultraviolet detection.

Results are given as mean (SEM). For colonocytes incubated in the presence of exogenous CoA and ATP, treatment with NaHS significantly diminished 14CO2 production (control 0.97 (0.06) mumol/g dry weight cells/min, treated 0.26 (0.09) mumol/g dry weight cells/min, p = 0.0019), was associated with an increase in butyryl-CoA concentrations in the final reaction mixture at 10 minutes (control 2.55 (0.28) mumol/g dry weight cells, treated 3.32 (0.32) mumol/g dry weight cells, p = 0.002), and a reduction in crotonyl-CoA concentrations (control 0.274 (0.02) mumol/g dry weight cells, treated 0.120 (0.04) mumol/g dry weight cells, p = 0.008). The mean concentration of acetyl-CoA in the reaction mixture at 10 minutes was not significantly different between control and sulphide treated incubations. There were no significant differences in acyl-CoA ester profiles observed when cells were incubated in the absence of exogenous CoA and ATP.

These results support the view that sulphides inhibit n-butyrate oxidation in colonic epithelial cells by inhibiting short chain acyl dehydrogenation of activated fatty acids.