(Ca+Mg)ATPase and calcium influx in erythrocytes of patients with idiopathic hypercalciuria.
Increased erythrocyte (Ca+Mg)ATPase activity was previously observed in idiopathic hypercalciuria. In order to verify if this alteration is a primary or a secondary event, we studied Sr influx in erythrocytes from subjects with idiopathic hypercalciuria. (Ca+Mg)ATPase activity was significantly higher in hypercalciuric than in hypercalciuric than in normocalciuric subjects whereas no difference in Sr influx was found between the two groups. (Ca+Mg)ATPase activity positively correlated with the erythrocyte Sr content found after 5 min of incubation and with urine Ca excretion. The normal Sr permeability suggests that (Ca+Mg)ATPase is primarily altered in idiopathic hypercalciuria. The primary increase of (Ca+Mg)ATPase activity may enhance passive Ca influx by reduction of cellular Ca concentration. It may induce a defect in cellular Ca metabolism that may cause idiopathic hypercalciuria by stimulating bone Ca turn-over and enteral Ca absorption.
Vezzoli
G
G
Department of Nephrology Dialysis and Hypertension, S. Raffaele Scientific Institute, University of Milano, Italy.
Reina
M C
MC
Zerbi
S
S
Spaventa
R
R
Soldati
L
L
Cusi
D
D
Bianchi
G
G
D001692:Biological Transport; D017301:Ca(2+) Mg(2+)-ATPase / Q000097:blood*; D002118:Calcium / Q000097:blood* / Q000652:urine*; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D013324:Strontium / Q000378:metabolism
D010281:Parathyroid Hormone; D010710:Phosphates; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium; D013324:Strontium