{"id":"1af4fef9-4770-52f7-b205-f273f4c7aea2","stable_key":"1ff3a29f-ef80-5bff-9300-30b98c60b90d:strontium-renal-competition","predicate":"competitively_inhibits","statement":"Calcium and strontium each competitively inhibited uptake of the other in the renal-vesicle assay, increasing apparent half-saturation concentration without changing maximum velocity.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"5e99d3ea-6035-52a0-9772-da740aedac3c","mechanism_event_label":"The two ions compete for access to the same transport machinery.","subject":{"id":"97607549-3a37-544e-b6e6-266887f7c35f","slug":"strontium-ion","display_name":"Strontium ion / Sr2+","entity_type_key":"ion"},"object":{"id":"6b7bfcad-49ae-5b88-9c65-2d5fdeb848df","slug":"renal-vesicle-calcium-uptake","display_name":"Calcium uptake by renal basolateral membrane vesicles","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"5e99d3ea-6035-52a0-9772-da740aedac3c","stable_key":"1ff3a29f-ef80-5bff-9300-30b98c60b90d:strontium-renal-competition-event","event_type":"observed_relationship","label":"The two ions compete for access to the same transport machinery.","description":"Calcium and strontium each competitively inhibited uptake of the other in the renal-vesicle assay, increasing apparent half-saturation concentration without changing maximum velocity.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"97607549-3a37-544e-b6e6-266887f7c35f","slug":"strontium-ion","display_name":"Strontium ion / Sr2+","entity_type_key":"ion"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"6b7bfcad-49ae-5b88-9c65-2d5fdeb848df","slug":"renal-vesicle-calcium-uptake","display_name":"Calcium uptake by renal basolateral membrane vesicles","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"2ca2864b-1ef0-54e4-8397-1dbe7207a0d2","slug":"strontium","display_name":"Strontium","entity_type_key":"nutrient_element"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"e359bc15-e675-5d83-b0fe-1d70814e130b","slug":"calcium-ion","display_name":"Calcium ion","entity_type_key":"ion"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"d46a8d5b-1a2d-5e93-8b06-a005ee199285","slug":"renal-basolateral-calcium-magnesium-atpase-assay","display_name":"Renal proximal-tubule basolateral calcium/magnesium ATPase assay preparation","entity_type_key":"protein_set"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Radiotracer uptake in isolated renal basolateral membranes.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Shared-site kinetics do not establish a dietary calcium-loss threshold or quantify whole-kidney excretion.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Strontium collection; molecular form, preparation, species, exposure and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"strontium","display_name":"Strontium","entity_type_key":"nutrient_element"}},{"dimension":"plain_language","value_text":"The two ions compete for access to the same transport machinery.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"A Comparison Between Calcium and Strontium Transport by the (Ca2+ + Mg2+)ATPase of the Basolateral Plasma Membrane of Renal Proximal Convoluted Tubules. · 2025 · https://pubmed.ncbi.nlm.nih.gov/40277992/ · DOI 10.3390/membranes15040122","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"7cdea7c6-7ef6-5355-8bda-ceb8ef99a345","evidence_kind":"source_excerpt","locator":"Lines 22-28","start_line":22,"end_line":28,"excerpt":"## strontium-renal-competition\nThe two ions compete for access to the same transport machinery.\nCalcium and strontium each competitively inhibited uptake of the other in the renal-vesicle assay, increasing apparent half-saturation concentration without changing maximum velocity.\nModel: Radiotracer uptake in isolated renal basolateral membranes.\nLimitations: Shared-site kinetics do not establish a dietary calcium-loss threshold or quantify whole-kidney excretion.\nEvidence access: Primary full text\nA Comparison Between Calcium and Strontium Transport by the (Ca2+ + Mg2+)ATPase of the Basolateral Plasma Membrane of Renal Proximal Convoluted Tubules. · 2025 · https://pubmed.ncbi.nlm.nih.gov/40277992/ · DOI 10.3390/membranes15040122","model_system":"Radiotracer uptake in isolated renal basolateral membranes.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"43ef0fe7-eb6c-5346-8381-f7694733b4dc","stable_key":"import-1ff3a29f-ef80-5bff-9300-30b98c60b90d","title":"Strontium: calcium interactions, cellular mechanisms and mineralization (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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