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Updated: Aug 11, 2026

Isolation of Pulmonary Artery Smooth Muscle Cells from Neonatal Mice
Published on: October 19, 2013
Nitric oxide synthase is absent in only a subset of cases of pyloric stenosis
R Subramaniam1, C M Doig, L Moore
1Department of Paediatric Surgery and Pathology, Booth Hall Children's Hospital, Blackley, Manchester, England.
Purpose:
The aim of this study was to study nitric oxide synthase (NOS) immunohistochemistry in the pyloric muscle and establish the role of nitric oxide in pyloric stenosis.
Methods:
Pyloric muscle biopsy specimens were obtained from 20 patients with pyloric stenosis during pyloromyotomy. Ten control specimens without pyloric disease were obtained from autopsy performed less than 4 hours after death on age-matched babies who died of other causes. Tissues were fixed in 4% paraformaldehyde immediately. A monoclonal antibody against the neuronal form of NOS (bNOS) was used for immunohistochemistry.
Results:
Immunohistochemistry showed activity of bNOS in the control specimens and some pyloric stenosis specimens. This shows that NOS is present in the pylorus in normal cases as well as in a few cases of pyloric stenosis.
Conclusions:
NOS deficiency leading to lack of locally available nitric oxide causes a failure of smooth muscle relaxation. This may account for the cause of pyloric stenosis in infants. However, this study shows that this is true probably only in a subset of cases. The etiology of pyloric stenosis may still be multifactorial. Further investigations are required regarding the etiology of pyloric stenosis. J Pediatr Surg 36:616-619.
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