Effect of some amino acids on the rectal irritation caused by sodium caprate in conscious rats

The effects of some amino acids such as L-glutamine (Gln), L-arginine (Arg) and L-methionine (Met) on rectal irritation caused by sodium caprate were studied in rats. Rectal irritation was assessed by the balloon method in fasting conscious rats. This method is based on measuring rectal contractions due to possible irritation caused by the presence of drugs and/or adjuvants in the rectum. Strong contractions were observed after rectal administration of an aqueous solution of 100 mM sodium caprate. However, the presence of Gln, Arg or Met (100 mM) in sodium caprate (100 mM) solution resulted in a significant decrease in the intensity of the rectal contraction caused by sodium caprate. The rectal absorption-promoting effect of sodium caprate on 6-carboxyfluorescein (6-CF) was examined following administration with amino acids in rats. The absorption of 6-CF was not influenced by the concurrent administration of amino acids. In addition, the rectal tissue interaction of sodium caprate, with or without Gln, was examined. The concentration of sodium caprate in rectal tissue was reduced by the presence of Gln.