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Titolo:
DECREASED POTASSIUM STIMULATES BONE-RESORPTION
Autore:
BUSHINSKY DA; RIORDON DR; CHAN JS; KRIEGER NS;
Indirizzi:
UNIV ROCHESTER,SCH MED,DEPT MED,NEPHROL UNIT,601 ELMWOOD AVE,BOX 675 ROCHESTER NY 14642
Titolo Testata:
American journal of physiology. Renal, fluid and electrolyte physiology
fascicolo: 6, volume: 41, anno: 1997,
pagine: 774 - 780
SICI:
0363-6127(1997)41:6<774:DPSB>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
URINARY CALCIUM EXCRETION; INTRACELLULAR PH; MOUSE CALVARIA; HEALTHY-ADULTS; ACIDOSIS; INVITRO; RATS; BICARBONATE; DEPRIVATION; DEPLETION;
Keywords:
CALCIUM FLUX; ACIDOSIS; HYPOKALEMIA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
D.A. Bushinsky et al., "DECREASED POTASSIUM STIMULATES BONE-RESORPTION", American journal of physiology. Renal, fluid and electrolyte physiology, 41(6), 1997, pp. 774-780

Abstract

Metabolic acidosis induces net calcium efflux (J(Ca)(+)) from cultured bone, in part, through an increase in osteoclastic resorption and a decrease in osteoblastic formation. In humans provision of base as potassium (K+) citrate, but not sodium (Na+) citrate, reduces urine Ca (U-Ca), and oral KHCO3 decreases bone resorption and Uc, in postmenopausal women. Potassium deprivation alone leads to an increase in U-Ca. Todetermine whether decreased extracellular K+ concentration ([K+]) at a constant pH, P-CO2, and [HCO2-] alters J(Ca)(+) and bone cell activity, we measured J(Ca)(+), osteoblastic collagen synthesis, and osteoclastic beta-glucuronidase release from neonatal mouse calvariae cultured for 48 h in medium of varying [K+]. Calvariae were cultured in control medium (approximate to 4 mM [K+]) or medium with mildly low K+ (MLK, approximate to 3 mM: [K+]), very low K+ (VLK, approximate to 2 mM [K]), or extremely low K+ (ELK, approximate to 1 mM [K+]) (n greater than or equal to 9 in each group). Compared with control, ELK, but not MLK or VLK, resulted in a marked increase in J(Ca)(+) and an increase in beta-glucuronidase release and a decrease in collagen synthesis. J(Ca)(+), was correlated directly with medium beta-glucuronidase activityand inversely with collagen synthesis. To determine whether the reduction in medium [K+] was associated with a decrease in intracellular pH(pH(i)), we measured pH(i) in MC3T3-E1 cells, a mouse osteoblastic cell line. Incubation in 1 mM [K+] led to a significant decrease in pH(i) compared with 3 mM [K+]. Thus incubation in a reduced [K+] medium stimulates J(Ca)(+) and osteoclastic enzyme release and inhibits osteoblastic collagen synthesis, which may be mediated by a reduction in bonecell pH.

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Documento generato il 01/12/20 alle ore 10:49:33