ABSENCE OF NADPH-DIAPHORASE ACTIVITY IN INTERNAL ANAL-SPHINCTER (IAS)ACHALASIA

We studied the internal anal sphincter (IAS) muscle from 10 patients w ith achalasia and five normal controls using histochemical staining fo r NADPH-diaphorase and acetylcholinesterase (AChE). Normal control IAS muscle contained occasional AChE-positive nerve fibers, whereas IAS a chalasia specimens demonstrated prominent AChE-positive nerve fibers i n muscle layers. NADPH-diaphorase activity was strongly expressed in n erves in the normal IAS muscle but was absent or scanty in the muscle of patients with IAS achalasia. Our findings of increased AChE-positiv e nerves and the absence of NADPH-diaphorase activity taken in conjunc tion with reports of abnormal peptidergic innervation indicate that co mplex neural abnormalities occur in IAS achalasia. The primary event r emains obscure, but it is possible that a single defect, such as nitre rgic nerve depletion, may lead to compensatory changes in the other ne rve fibers.