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Abstract
OBJECTIVE To evaluate redox status and muscular mitochondrial abnormalities in patients with polymyalgia rheumatica (PMR).
METHODS Prospective evaluation of deltoid muscle biopsy in 15 patients with PMR. Fifteen subjects matched for age and sex, with histologically normal muscle and without clinical evidence of myopathy, were used as controls. Cryostat sections of muscle were processed for conventional dyes, cytochromec oxidase (COX), usual histochemical reactions, and Sudan black. A total of 300–800 fibres was examined in each case. Blood lactate, pyruvate, and lactate/pyruvate ratio were determined in all patients.
RESULTS Ragged red fibres were found in eight patients with PMR and accounted for 0–0.5% of fibres. Focal COX deficiency was found in 14 (93%) of 15 patients and in nine (60%) of 15 controls. COX deficient fibres were more common in patients with PMR (range 0–2.5%; mean 0.9%) than in controls (range 0–1.2%; mean 0.3%) (pairedt test, p=0.001). Seven (47%) of 15 patients had high blood lactate levels (1.50–2.60 mmol/l) or high blood lactate/pyruvate ratios (22–25).
CONCLUSIONS PMR is associated with mitochondrial abnormalities not solely related to the aging process.
- polymyalgia rheumatica
- cytochrome c oxidase
- mitochondria
- lactate