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This Article Full Text Full Text (PDF) All Versions of this Article: 285/4/F711    most recent 00096.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Welch, B. D. Articles by Kishore, B. K. Search for Related Content PubMed PubMed Citation Articles by Welch, B. D. Articles by Kishore, B. K.

P2Y₂ receptor-stimulated release of prostaglandin E₂ by rat inner medullary collecting duct preparations

Departments of ¹Internal Medicine, ⁶Physiology, and ³Neurobiology and Anatomy, University of Utah Health Sciences Center, Salt Lake City 84132; ²Nephrology Research and ⁵Geriatric Research, Education, and Clinical Center, Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah 84148; and ⁵Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267

Submitted 15 March 2003 ; accepted in final form 15 May 2003

Extracellular nucleotides, acting through the P2Y₂ receptor and the associated phosphoinositide-Ca²⁺ signaling pathway, inhibit AVP-stimulated osmotic water permeability in rat inner medullary collecting duct (IMCD). Because a rise in intracellular Ca²⁺ is frequently associated with enhanced arachidonic acid metabolism, we examined the effect of activation of the P2Y₂ receptor on release of PGE₂ in freshly prepared rat IMCD suspensions. Unstimulated IMCD released moderate, but significant, amounts of PGE₂, which were more sensitive to cyclooxygenase (COX)-2 than COX-1 inhibition. Agonist activation of P2Y₂ receptor by adenosine 5'-O-(3-thiotriphosphate) enhanced release of PGE₂ from IMCD in a time- and concentration-dependent fashion. Purinergic-stimulated release of PGE₂ was completely blocked by nonspecific COX inhibitors (flurbiprofen and 2-acetoxyphenylhept-2-ynyl sulfide). Differential COX inhibition studies revealed that purinergic-stimulated release of PGE₂ was more sensitive to a COX-1-specific inhibitor (valeroyl salicylate) than a COX-2-specific inhibitor (NS-398). Thus purinergic stimulation resulted in significantly more release of PGE₂ in the presence of COX-2 inhibitor than COX-1 inhibitor. If it is assumed that increased release of PGE₂ is related to its increased production, our results suggest that purinergic stimulation of IMCD results in enhanced production and release of PGE₂ in a COX-1-dependent fashion. Because PGE₂ is known to affect transport of water, salt, and urea in IMCD, interaction of the purinergic system with the prostanoid system in IMCD can modulate handling of water, salt, and urea by IMCD and, thus, may constitute an AVP-independent regulatory mechanism.

cyclooxygenases; arachidonic acid; extracellular nucleotides; arginine vasopressin; purinergic receptor