Different populations of interstitial cells (ICs) may serve as gut pacemake
rs or as intermediaries between enteric nerves and smooth muscle cells. How
ever, very little is known about the substances that ICs might use to commu
nicate with other cells and no data are available in humans. Because carbon
monoxide (CO) is emerging as a putative mediator in the regulation of gast
rointestinal motility, this study examined the presence of heme oxygenase (
HO2), the constitutive form of the enzyme for CO production, in human stoma
ch with particular attention to ICs. The distribution of HO2 in nerves and
ICs in human antrum was studied using specific antibodies. The immunostaini
ng was observed using confocal laser scanning microscopy. HO2 immunoreactiv
ity 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 sur
rounding 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.