Developmental changes of nitric oxide-sensitive guanylyl cyclase expression in pulmonary arteries

Inhaled nitric oxide (NO) is known to influence the contractile state of pu lmonary arteries most likely by activation of soluble guanylyl cyclase (sGC ) in smooth muscle cells. However, the cellular distribution of sGC has not been determined empirically, due to a lack of specific antibodies. Here, w e describe a novel antibody directed against the beta (1) subunit of sGC to study the cellular distribution of sGC in lung during development. Using t he novel antibody, the enzyme was demonstrated in fetal, neonatal, and adul t lungs by Western blot, showing maximum expression in neonatal lung. These data were confirmed by measurements of sGC activity. In pulmonary arteries of fetal lung sGC-beta (1) immunoreactivity was present in smooth muscle c ells and absent in endothelial cells. With postnatal development an increas e in immunoreactivity in endothelial cells and a reciprocal decrease in smo oth muscle cells was apparent. The reported changes in sGC expression likel y contribute to the known age-dependent differences in response to inhaled NO. (C) 2001 Academic Press.