Fig. 9.

Summary schematic. While NTPDase1 (magenta) is expressed by intraepithelial lymphocytes (IEL), muscularis macrophages (Mϴ), and smooth muscle cells, NTPDase2 (green) is expressed by all subtypes of enteric glial cells (EGC) such as mucosal (type III), intramuscular (type IV) and within myenteric ganglia (type I), and platelet-derived growth factor receptor α positive (PDGFRα+) cells. The enzymes are also expressed by vasculature, NTPDase1 by endothelial cells (EC) and NTPDase2 by pericytes (P). In basal conditions (left, unshaded side) most of the extracellular ATP is hydrolyzed into AMP by NTPDase1. This kind of ATP degradation supports physiological circular muscle relaxation and slow phase of inhibitory junction potentials (IJPs). There is also an effect of NTPDase2 on muscle relaxation and fast phase of IJPs. After inflammation (right, shaded side), however, abundant extracellular ATP is mostly degraded into ADP by NTPDase2. This process protects and/or aids recovery of intestinal barrier function. In addition, NTPDase1 is involved in regulation of circular smooth muscle contractions in health and during the recovery of inflammation (not drawn, see Table 5). The schematic is a summary of this study and previous work (10, 61, 64, 69). Created with BioRender.com and not drawn to scale.