Distribution of heme oxygenase 2 in nerves and c-kit(+) interstitial cells in human stomach.

Different populations of interstitial cells (ICs) may serve as gut pacemakers or as intermediaries between enteric nerves and smooth muscle cells. However, very little is known about the substances that ICs might use to communicate with other cells and no data are available in humans. Because carbon monoxide (CO) is emerging as a putative mediator in the regulation of gastrointestinal motility, this study examined the presence of heme oxygenase (HO2), the constitutive form of the enzyme for CO production, in human stomach with particular attention to ICs. The distribution of HO2 in nerves and ICs in human antrum was studied using specific antibodies. The immunostaining was observed using confocal laser scanning microscopy. HO2 immunoreactivity was found in myenteric neurons and nerve fibers supplying the circular muscle layer and in intramuscular c-kit(+) ICs, but not in c-kit(+) ICs surrounding the myenteric ganglia. The presence of HO2 in different cell types suggests that CO may serve as an intercellular messenger between myenteric neurons and ICs and between ICs and smooth muscle cells in human stomach.