title: Effect of luminal Cl- and Ca2+ on tubuloglomerular feedback mechanism.
abstract: We dissected and perfused in vitro rabbit cortical thick ascending limbs (CTAL) and distal convoluted tubule with the glomerulus attached intact. Basolateral membrane voltage (Vbl) and intracellular Ca2+ concentration ([Ca2+]i) in macula densa (MD) cells were measured with microelectrodes and microscope photometry, respectively. Our data suggest that the apical membrane of MD cell has a Ca2+ entry pathway, and that the basolateral membrane of MD cell has a Cl- conductance, which may be regulated by the [Ca2+]i in MD cell. We next evaluated by measuring the afferent arteriolar diameter with video camera monitoring whether the change in Ca2+ concentration of macula densa tubular lumen indeed affect tubuloglomerular feedback. The data suggest that the changes in luminal Ca2+ as well as Cl- concentration at macula densa independently alter the afferent arteriolar diameter, thus may affect the single nephron glomerular filtration rate.
authors.affiliation: Third Department of Internal Medicine, Kumamoto University Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Naruse
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Nakayama
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Kurokawa
mesh_terms: D000818:Animals; D001158:Arteries / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology*; D002712:Chlorides / Q000494:pharmacology*; D005246:Feedback; D007668:Kidney / Q000502:physiology*; D008954:Models, Biological; D009399:Nephrons / Q000187:drug effects; D011817:Rabbits
chemical_list: D002712:Chlorides; D002118:Calcium