Dietary potassium restriction causes hypercalciuria, hypocalcemia and bone loss in male mice

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Abstract

Loss of bone mass has a devastating effect on quality of life. Higher potassium (K+) intake is positively correlated with bone health. Here, we investigated whether kidney calcium (Ca2+) and phosphate (Pi) handling mechanisms mediate dietary K+ effects. Kidney Ca2+ and Pi handling proteins were altered in abundance in mice fed a 0% K+ diet for 2 weeks. In mice fed a 0.1% K+ diet for 4 or 8 weeks, urinary Ca2+ excretion increased, plasma Ca2+ levels were lower and plasma parathyroid hormone (PTH) levels were higher relative to control 1% K+ fed mice. The 0.1% K+ fed mice had greater excretion of the bone resorption marker deoxypyridinoline, increased osteoclast number, and decreased total femoral bone mineral density. During chronic low K+ intake, major changes in renal Ca2+ and Pi transport pathways were absent, except higher abundances of the sodium-potassium-chloride co-transporter (NKCC2) and the sodium-chloride co-transporter (NCC), in line with their role in kidney Ca2+ handling. Low dietary K+ induced hypocalcemia and changes in PTH were absent in mice with constitutively active NCC, supporting its role in mediating low K+ effects on Ca2+ homeostasis. Our study provides insights into the management of bone disorders in conditions of chronic electrolyte imbalance.

Authors

Sathish K. Murali, Mariavittoria D'Acierno, Xiang Zheng, Lena K. Rosenbaek, Louise N. Odgaard, Paul Richard Grimm, Alice Ramesova, Robert Little, Judith Radloff, Paul A. Welling, Qi Wu, Reinhold G. Erben, Robert A. Fenton