title: AVP-stimulated nucleotide secretion in perfused mouse medullary thick ascending limb and cortical collecting duct.
abstract: Extracellular nucleotides are local, short-lived signaling molecules that inhibit renal tubular transport via both luminal and basolateral P2 receptors. Apparently, the renal epithelium itself is able to release nucleotides. The mechanism and circumstances under which nucleotide release is stimulated remain elusive. Here, we investigate the phenomenon of nucleotide secretion in intact, perfused mouse medullary thick ascending limb (mTAL) and cortical collecting duct (CCD). The nucleotide secretion was monitored by a biosensor adapted to register nucleotides in the tubular outflow. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured simultaneously in the biosensor cells and the renal tubule with fluo 4. We were able to identify spontaneous tubular nucleotide secretion in resting perfused mTAL. In this preparation, 10 nM AVP and 1-desamino-8-D-arginine vasopressin (dDAVP) induced robust [Ca(2+)](i) oscillations, whereas AVP in the CCD induced large, slow, and transient [Ca(2+)](i) elevations. Importantly, we identify that AVP/dDAVP triggers tubular secretion of nucleotides in the mTAL. After addition of AVP/dDAVP, the biosensor registered bursts of nucleotides in the tubular perfusate, corresponding to a tubular nucleotide concentration of approximately 0.2-0.3 microM. A very similar response was observed after AVP stimulation of CCDs. Thus AVP stimulated tubular secretion of nucleotides in a burst-like pattern with peak tubular nucleotide concentrations in the low-micromolar range. We speculate that local nucleotide signaling is an intrinsic feedback element of hormonal control of renal tubular transport.
authors.affiliation: Department of Physiology and Biophysics, The Water and Salt Research Center, Aarhus University, Aarhus C, Denmark.
authors.forename: Elvin
authors.initials: E
authors.lastname: Odgaard
authors.forename: Helle A
authors.initials: HA
authors.lastname: Praetorius
authors.forename: Jens
authors.initials: J
authors.lastname: Leipziger
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000814:Aniline Compounds; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D001692:Biological Transport; D015374:Biosensing Techniques; D020013:Calcium Signaling; D002460:Cell Line; D003894:Deamino Arginine Vasopressin / Q000378:metabolism; D025461:Feedback, Physiological; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D066298:In Vitro Techniques; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D008138:Loop of Henle / Q000378:metabolism*; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D009711:Nucleotides / Q000378:metabolism*; D010477:Perfusion; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2; D013997:Time Factors; D014162:Transfection; D014544:Uridine Triphosphate / Q000378:metabolism; D014966:Xanthenes
chemical_list: D000814:Aniline Compounds; C409648:Fluo 4; D005456:Fluorescent Dyes; D009711:Nucleotides; C546385:P2RY2 protein, human; C546386:P2ry2 protein, mouse; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D014966:Xanthenes; D001127:Arginine Vasopressin; D000255:Adenosine Triphosphate; D003894:Deamino Arginine Vasopressin; D014544:Uridine Triphosphate