Abstract 654

It has been assumed that the sole origin of butyric acid for mammals is from bacterial fermentation of carbohydrate, primarily in the colonic lumen. Thus, the relevance of butyric acid's biochemical and molecular effects on gene transcription, cell proliferation, and cell differentiation in cell culture (inhibition of histidine deacetylase) has been thought to be confined mainly to the colonocyte. As part of a goal to develop a simpler method of measuring colonic production of butyric acid using a single, stable isotope dilution technique, we studied 4, acutely anesthetized piglets (aged 24-27 d) who were either sow-reared (N=2) or fed sow milk replacement formula. [1-13C]-butyric acid was infused (120 min) into the jejunal mesenteric vein while the entire colonic vasculature was clamped. Vital signs remained stable and plateau enrichment (moles per cent excess, MPE) of butyric acid was observed in both the portal vein (PV) and in an artery (A). In each piglet, there was a clear fall in MPE from PV to A. Mean (±SEM) MPE in the PV and A was respectively 95.3± 2.0 and 79.7± 1.9 (P=0.002)(A/PV = 0.80±0.02). These data provide consistent preliminary evidence for a mammalian source of butyric acid, which should be confirmed by identifying the gene for butyric acid synthesis in the mammalian genome. This observation could have significance to the development of cell differentiation in multi-cellular organisms.

Funded by: CHRF; Ross Product Division of Abbott Laboratories; CCFA