Fatal gastrointestinal obstruction and hypertension in mice lacking nitric oxide-sensitive guanylyl cyclase

The signaling molecule nitric oxide (NO), first described as endothelium-derived relaxing factor (EDRF), acts as physiological activator of NO-sensitive guanylyl cyclase (NO-GC) in the cardiovascular, gastrointestinal, and nervous systems. Besides NO-GC, other NO targets have been proposed; however, their particular contribution still remains unclear. Here, we generated mice deficient for the beta1 subunit of NO-GC, which resulted in complete loss of the enzyme. GC-KO mice have a life span of 3-4 weeks but then die because of intestinal dysmotility; however, they can be rescued by feeding them a fiber-free diet. Apparently, NO-GC is absolutely vital for the maintenance of normal peristalsis of the gut. GC-KO mice show a pronounced increase in blood pressure, underlining the importance of NO in the regulation of smooth muscle tone in vivo. The lack of an NO effect on aortic relaxation and platelet aggregation confirms NO-GC as the only NO target regulating these two functions, excluding cGMP-independent mechanisms. Our knockout model completely disrupts the NO/cGMP signaling cascade and provides evidence for the unique role of NO-GC as NO receptor.

Familial pyloric atresia: report of a family and review of the literature

Pyloric atresia occurs in one in a million births and usually occurs sporadically. We report a family with nine affected members and review the literature for all reported familial cases. The article stresses the possibility of recurrence of pyloric atresia in the progeny of consanguinous parents, with an emphasis on prenatal diagnosis and counseling, diagnosis of the entity in neonates, associated conditions, and prognosis in sporadic and familial cases. A high index of suspicion in affected families contributes to the early diagnosis and treatment with a great impact on outcome.