M. Shakibaei et al., COMPARATIVE-EVALUATION OF ULTRASTRUCTURAL-CHANGES IN ARTICULAR-CARTILAGE OF OFLOXACIN-TREATED AND MAGNESIUM-DEFICIENT IMMATURE RATS, Toxicologic pathology, 24(5), 1996, pp. 580-587
Ultrastructural changes in immature articular cartilage were studied a
fter treatment of 5-wk-old rats with ofloxacin-a fluoroquinolone-and i
n magnesium deficiency. Magnesium deficiency was induced by feeding a
magnesium-deficient diet for 9 days; the condition was confirmed by me
asuring the concentrations of the mineral in plasma, bone, and cartila
ge samples of the animals by atomic absorption spectrophotometry. Oral
administration of single doses of 600 or 1,200 mg ofloxacin/kg body w
eight and magnesium deficiency were sufficient to induce gross structu
ral cartilage defects. Alterations observed on the ultrastructural lev
el showed striking similarities in magnesium-deficient rats and in rat
s treated with single doses of 600 mg ofloxacin/kg body weight. Typica
l observations were (a) bundle-shaped, electron-dense aggregates on th
e surface and in the cytoplasm of chondrocytes, (b) detachment of the
cell membrane from the matrix and necrotic chondrocytes, (c) reduction
of the extracellular matrix, and (d) swelling of cell organelles such
as mitochondria. These findings further substantiate the histological
finding that quinolone treatment and a dietarily induced magnesium-de
ficiency induce indistinguishable pathological conditions in immature
joint cartilage, and they suggest that quinolone-induced arthropathy i
s probably caused by a reduction of functionally available magnesium (
ionized Mg2+) in cartilage (42). Furthermore, they provide a basis for
aimed studies with human cartilage samples from quinolone-treated pat
ients that might be available postmortally or after hip replacement su
rgery.