radio-receptor-assay with ( 3h ) 2-d-ala-5-d-leu-enkephalin revealed enkephalin binding sites in the submucosa plus muscularis mucosae ( kd = 3.6 nmol l-1 ; vmax = 7.3 fmol mg-1 ) and in the lamina propria mucosae ( kd = 4.2 nmol l-1 ;
C0014294
leu-enkephalin
C0014298
enkephalin