Failure of cholinergic stimulation to induce a secretory response from the rectal mucosa in cystic fibrosis

Abstract

The secretory response to cholinergic stimulation was investigated in rectal biopsy specimens from children with cystic fibrosis and a control group using a modified Ussing chamber technique. Acetylcholine (10-3 mol/1) increased the short circuit current in 12 control specimens by mean (SEM) 830· 0 (16·4) μA/cm2, but samples from five children with cystic fibrosis failed to exhibit such a response (-1.4 (3·2) μA/cm2). Amiloride (10-4 mol/1), which will inhibit electrogenic sodium absorption in viable tissues, caused similar reductions in the short circuit current of both control and cystic fibrosis tissues (control=-37.7 (7.7) μA/cm2; cystic fibrosis=-44·0 (9·3) μA/cm 2). Thus, the failure ofchloride secretion observed in the small intestine also exists in the rectal mucosa. This observation could be used both to aid diagnosis and to study the basic defect.