title: Effects of calcium on ADH action in the cortical collecting tubule perfused in vitro.
abstract: To test the effects of calcium on ADH action in an in vitro mammalian system, the rabbit cortical collecting tubule was studied. After 25 microunits/ml ADH (n=8) in the presence of 1.25 mM calcium bath, water flow (Jv) rose to 1.56 +/- 0.34 nl.mm-1. min-1 and hydraulic conductivity (Lp, cm.s-1.atm-1 X 10(7)) rose to 123 +/- 22. After 25 microunits/ml ADH in the presence of 3.75 mM calcium bath (n=7), Jv rose to 2.96 +/- 0.6 nl.mm-1.min-1 (P less than 0.05 vs. control) and Lp rose to 286 +/- 62 cm.s-1.atm-1 X 10(7) (P less than 0.02 vs. 1.25 mM bath calcium control). Tubules (n=6) perfused with 3.75 mM Ca and bathed in 3.75 mM Ca also showed an Lp of 279 +/- 82 cm.s-1.atm-1 X 10 (7) following 25 microunits/ml ADH. Tubules similarly studied in 1.25 (n=6) or 3.75 mM Ca (n=6) bath but treated with 10(-4) M 8-[p-chlorophenylthio]cAMP demonstrated Lp of 222 +/- 26 and 235 +/- 37 cm.s-1.atm-1 X 10(7), respectively. These data suggest that increased bath Ca enhances ADH- but not cAMP-stimulated water flow in the rabbit cortical collecting tubule. High perfusate Ca2+ does not alter the stimulatory effect of elevated peritubular Ca2+.
mesh_terms: D000818:Animals; D001834:Body Water / Q000502:physiology; D002118:Calcium / Q000494:pharmacology*; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000187:drug effects / Q000502:physiology*; D007684:Kidney Tubules / Q000187:drug effects / Q000502:physiology*; D010477:Perfusion; D011817:Rabbits; D013873:Thionucleotides / Q000494:pharmacology*; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D013873:Thionucleotides; D014667:Vasopressins; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D002118:Calcium