Involvement of multiple receptors in the actions of extracellular ATP: the example of vascular endothelial cells

Interplay between the NO pathway and elevated [Ca2+]i enhances ciliary activity in rabbit trachea

“…These results suggest that PKC is not involved in ciliary activation induced by extracellular ATP in rabbit airway. It is well established that a rise in [Ca¥]é can activate several types of AC (Antoni, 1997) andÏor isoenzymes of NOS (Motte et al 1995), leading to the stimulation of PKA and PKG, respectively. Inhibition of PKA by Rp-cAMPS failed to attenuate the rise in [Ca¥]é or the CBF enhancement caused by extracellular ATP, indicating that PKA is not involved in this process.…”

“…Consistent with this conclusion, preventing change in [Ca¥]é by loading the cells with the Ca¥ chelator BAPTA AM abolished CBF enhancement induced by extracellular ATP (data not shown). It has been shown that NOS can be directly activated by a rise in [Ca¥]é (Motte et al 1995), raising the possibility that the initial increase in [Ca¥]é is needed to activate the NO pathway. To test this possibility, the ATP-induced signal transduction pathway was bypassed by elevating [Ca¥]é with ionomycin in Ringer solution.…”

ATP-dependent Activation of KCa and ROMK-type KATP Channels in Human Submandibular Gland Ductal Cells

“…These data reveal a potentially new mechanism for K ϩ secretion in salivary epithelial cells. P2Y 1 , P2Y 2 (P 2U ), P2X 4 , and P2X 7 (P 2Z ) receptors are expressed in salivary glands (6 Fig. 3-5; also see Ref.…”

“…P2 receptors have been found in many epithelial cells, including those from various salivary glands. Four P2 receptors have been identified in salivary gland cells: P2Y 1 , P2Y 2 (P 2U ), P2X 4 , and P2X 7 (P 2Z ) (6). In rat parotid acinar cells, it has been reported that ATP primarily activates a Ca 2ϩ and Na ϩ -permeable cation channel via stimulation of P 2Z receptors.…”

“…Pharmacological studies with various ATP analogues have demonstrated two major groups of purinergic (P2) receptors: ionotropic receptors (P2X), associated with ligand-gated nonselective cation channel activity, and metabotropic receptors (P2Y), associated with activation of Gproteins (2)(3)(4)(5). In nonexcitable cells, extracellular ATP induces an elevation of cytosolic [Ca 2ϩ ] ([Ca 2ϩ ] i ) by two distinct mechanisms, either by activation of Ca 2ϩ release from intracellular Ca 2ϩ stores or via activation of Ca 2ϩ influx from the external medium (5,6).…”