title: Parathyroid hormone and calcium: interactions in the control of renin secretion in the isolated, nonfiltering rat kidney.
abstract: The present study was designed to characterize the interaction of calcium and PTH in the control of renin release in isolated rat kidneys perfused in a closed circuit at constant flow. Kidneys were rendered nonfiltering using low perfusion pressures (70 mm Hg) and a hyperoncotic perfusate (100 g/liter BSA). Under these conditions, differences in perfusion pressure were less than 9 mm Hg between control and PTH-treated kidneys over the 50 min of perfusion. In the absence of PTH, renin release was inversely correlated with ionized calcium (Ca2+) concentration, with the highest release of renin noted with 1 mM EGTA and no added calcium. Also, verapamil treatment markedly elevated renin release, even in the presence of 2 mM Ca2+. In contrast, renin secretion was strongly depressed by 20 nM BAY-K8644 in the perfusate. In medium containing normal calcium concentrations (1 mM Ca2+), rat PTH(1-34) induced a 2-fold greater renin accumulation than in the control, non-PTH-treated kidneys. Isoproterenol induced a 5-fold stimulation under the same conditions. In the 0 Ca2+/1 mM EGTA perfusion, PTH did not elevate renin secretion. Renin release in response to PTH in 2 mM Ca2+ was similar to that observed in the 1 mM Ca2+ perfusion. PTH also reversed the effects of BAY-K8644 to suppress renin release. In verapamil-treated kidneys, PTH failed to stimulate renin release. These results indicate that PTH stimulates renin release by a process independent of the baroreceptors and macula densa. The Ca2+ modulation of PTH-induced renin release is consistent with the reported ability of PTH to block calcium channels and relax vascular smooth muscle.
authors.affiliation: Laboratoire de Physiologie Renale Rene Leriche, Hospices Civils, Strasbourg, France.
authors.forename: J J
authors.initials: JJ
authors.lastname: Helwig
authors.forename: M J
authors.initials: MJ
authors.lastname: Musso
authors.forename: C
authors.initials: C
authors.lastname: Judes
authors.forename: G A
authors.initials: GA
authors.lastname: Nickols
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000378:metabolism*; D019379:Teriparatide; D014700:Verapamil / Q000494:pharmacology
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D019379:Teriparatide; D004533:Egtazic Acid; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D014700:Verapamil; D012083:Renin; D007545:Isoproterenol; D002118:Calcium