AJP - Endocrinology and Metabolism, Vol 258, Issue 4 E576-E581, Copyright © 1990 by American Physiological Society
Attenuated bone aluminum deposition in nonuremic beagles with reduced bone remodeling
L. D. Quarles
Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Excess bone aluminum accumulates in uremic subjects after
parathyroidectomy. To evaluate whether decreased bone remodeling caused by
parathyroidectomy augments bone aluminum deposition, we administered
aluminum chloride (0.75 mg/kg iv 3 times/wk) or vehicle to
thyroparathyroidectomized (TPTX) and sham-operated (Sham) nonuremic beagles
for 8 wk. TPTX alone effectively lowered plasma parathyroid hormone
concentrations (8.2 +/- 2.8 vs. 27 +/- 2.2 pg/ml) and consequently
suppressed bone remodeling, as evidenced by the diminished resorptive
surface (0.8 +/- 0.3 vs. 4.0 +/- 0.5%), osteoid surface (0.5 +/- 0.2 vs.
13.3 +/- 2.3%), and bone formation rate (1.8 +/- 0.6 vs. 15.5 +/- 2.2%/yr)
compared with untreated Shams. Aluminum treatment resulted in no further
suppression of bone remodeling in TPTX dogs and did not cause osteomalacia.
Aluminum-treated TPTX dogs, however, accumulated much less total bone (28.1
+/- 4.5 micrograms/g) and surface aluminum (3.8 +2- 1.4%) than similarly
treated Shams (61.4 +/- 5.6 micrograms/g; 12.2 +/- 2.7%, respectively)
despite displaying higher plasma aluminum concentrations (1,209 +/- 330 vs.
181 +/- 18 micrograms/l). These observations illustrate that diminished
bone turnover retards rather than augments bone aluminum accumulation. Thus
bone aluminum deposition after parathyroidectomy in uremic subjects is not
likely to be the result of passive aluminum accumulation on inactive bone
surfaces. Further studies are needed to determine whether factors, such as
prior bone aluminum accumulation and/or the degree of preexistent
hyperosteoidosis, modulate aluminum accumulation after parathyroidectomy.
