title: Biological fractionation of stable Ca isotopes in Göttingen minipigs as a physiological model for Ca homeostasis in humans.
abstract: In order to investigate fractionation of calcium (Ca) isotopes in vertebrates as a diagnostic tool to detect Ca metabolism dysfunction we analyzed the Ca isotopic composition (δ(44/40)Ca = [((44)Ca/(40)Ca)sample/((44)Ca/(40)Ca)reference]-1) of diet, faeces, blood, bones and urine from Göttingen minipigs, an animal model for human physiology. Samples of three groups were investigated: 1. control group (Con), 2. group with glucocorticosteroid induced osteoporosis (GIO) and 3. group with Ca and vitamin D deficiency induced osteomalacia (-CaD). In contrast to Con and GIO whose average δ(44/40)Cafaeces values (0.39 ± 0.13‰ and 0.28 ± 0.08‰, respectively) tend to be lower than their diet (0.47 ± 0.02‰), δ(44/40)Cafaeces of -CaD (-0.27 ± 0.21‰) was significantly lower than their δ(44/40)Cadiet (0.37 ± 0.03‰), but also lower than δ(44/40)Cafaeces of Con and GIO. We suggest that the low δ(44/40)Cafaeces of -CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage. Assuming that this endogenous Ca source is a common physiologic feature, a fractionation during Ca absorption is also required for explaining δ(44/40)Cafaeces of Con and GIO. The δ(44/40)Caurine of all groups are high (>2.0‰) reflecting preferential renal reabsorption of light Ca isotopes. In Göttingen minipigs we found a Ca isotope fractionation between blood and bones (Δ(44/40)Cablood-bone) of 0.68 ± 0.15‰.
authors.affiliation: a GEOMAR Helmholtz Centre of Ocean Research Kiel , Kiel , Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Heuser
authors.affiliation: a GEOMAR Helmholtz Centre of Ocean Research Kiel , Kiel , Germany.
authors.forename: Anton
authors.initials: A
authors.lastname: Eisenhauer
authors.affiliation: b Department of Physiology and Biochemistry of Nutrition, Max Rubner-Institut, Federal Research Institute of Nutrition and Food , Kiel , Germany.|c Department of Safety and Quality of Milk and Fish Products , Max Rubner-Institut, Federal Research Institute of Nutrition and Food , Kiel , Germany.
authors.forename: Katharina E
authors.initials: KE
authors.lastname: Scholz-Ahrens
authors.affiliation: b Department of Physiology and Biochemistry of Nutrition, Max Rubner-Institut, Federal Research Institute of Nutrition and Food , Kiel , Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schrezenmeir
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002127:Calcium Isotopes / Q000378:metabolism* / Q000493:pharmacokinetics; D006706:Homeostasis; D013552:Swine; D013556:Swine, Miniature
chemical_list: D002127:Calcium Isotopes; D002118:Calcium
keywords: Animals; calcium metabolism; calcium-40; calcium-44; isotope application in medicine; isotope ecology; stable isotope tracer techniques