The active contraction of vascular smooth muscle in response to elevation of luminal pressure, or stretch, is termed as the myogenic response. The mechanosensitive nonselective cation channels activated by membrane stretch (NSC_MS) have been considered as a candidate transducing mechanical events into the contractile response of the cells. Using the patch clamp technique, we recorded single-channel currents of NSC_MS with unitary conductance of about 25 pS in enzymatically dispersed pulmonary (PASMCs) and coronary arterial smooth muscle cells (CASMCs) from humanely killed rabbits (Park et al. 2003). Both the density and the pressure-sensitivity were higher in PASMCs than CASMCs. Considering the vaso-regulatory role of ATP released during hypoxic stimuli, we investigated whether the purinergic stimulation affects the activity of NSC_MS. When ATP (1 μM) was included in the pipette for the cell-attached configuration, the NP_O and the chance of recording the NSC_MS was largely increased in PASMCs while not in CASMCs. Similar effects were observed with UTP (1 μM ) applied through the patch pipette. However, the presence of α,Β-methylene-ATP, an P2X1/3 agonist, in the pipette did not show significant effect on NSC_MS in PASMCs in spite of the known expression of P2X1/3 receptors in PASMCs. The bath application of ATP or UTP in the cell-attached configuration had no significant effect on the NSC_MS, suggesting a membrane-delimited regulation mechanism. In summary, we found that the NSC_MS is more abundantly expressed in PASMCs than CASMCs, which might reflect that the pulmonary circulation has adapted to its low-pressure environment. In addition, the higher expression of NSC_MS and the positive regulation by purinoceptors (P2Y) suggest that these channels might play a specific role in the regulation of pulmonary circulation.