Molecular and biochemical characterization of prostacyclin receptors in rat kidney.
The prostacyclin (IP) message was detected by RT-PCR in the renal cortex, outer (OM) and inner medulla (IM), and in freshly isolated (IMCD-f) and cultured inner medullary collecting duct (IMCD-c), and also the E-prostanoid (EP)1,3,4 receptor subtypes, but not EP2. Digoxigenin in situ hybridization localized IP mRNA in the tubules of the OM and IM, and the vasculature, and also in the glomeruli, arteries, and tubules of the cortex. IP splice variants or subtypes could not be detected by RT-PCR followed by TA cloning, though several nonfunctional point mutations or single base pair deletions were observed. Iloprost (ILP), cicaprost (CCP), PGE2, and arginine vasopressin (AVP) stimulated cAMP in both IMCD preparations. In addition, AVP-stimulated cAMP in IMCD-f was inhibited by all three prostanoids, but not in IMCD-c. Calcium experiments were performed on IMCD-c or microdissected IMCD (IMCD-m). CCP, ILP, and PGE2 did not alter intracellular calcium concentration ([Ca2+]i) in IMCD-c. However, on IMCD-m, both PGE2 and ILP increased [Ca2+]i levels equipotently and CCP had no effect. Pretreatment with the EP1 antagonist AH-6809 indicates that the response to ILP and PGE2 is mediated via EP1. These results suggest that IP receptors in the rat IMCD mediate the cAMP but not calcium signaling linked to PGI2; to date no subtypes or splice variants have been identified.
Nasrallah
R
R
Department of Cellular and Molecular Medicine, Faculty of Medicine, and Kidney Research Centre, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5.
Zimpelmann
J
J
Singh
S
S
Hébert
R L
RL
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism; D008297:Male; D011453:Prostaglandins / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin / Q000187:drug effects / Q000378:metabolism*; D018078:Receptors, Prostaglandin E / Q000187:drug effects / Q000378:metabolism*; D058306:Receptors, Prostaglandin E, EP1 Subtype; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D011453:Prostaglandins; C545637:Ptger1 protein, rat; D012333:RNA, Messenger; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D001127:Arginine Vasopressin; D000242:Cyclic AMP; D002118:Calcium