Amino acid uptake in vitro by jejunal mucosa was stimulated by the addition of adenosine cyclic 3':5' monophosphate (cyclic AMP), dibutyryl cyclic AMP, theophylline, and cholera toxin. This stimulation appeared to be specific for neutral and dibasic amino acids, since the uptake of iminoamino acids and 3 O methylglucose 3 O methylglucose was unaffected. The enhanced uptake uptake correlated positively with tissue cyclic AMP levels but not with cyclic GMP. Kinetic studies demonstrated a decrease in K(t). There was cross inhibition between lysine and leucine for the stimulated (but not for unstimulated) uptake. The effect of theophylline was noted only in jejunum and not in ileum. Although ileal cAMP levels rose, neither influx nor efflux of amino acid was affected. The findings suggest that cyclic AMP mediates transport pathways at or near the brush border which are shared in part by dibasic and neutral amino acids.
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - 1973|