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Myoglobinuric acute renal failure (MARF) may develop after severe muscle injury. Heme oxygenase-1 (HO-1), a stress-response protein, has been implicated as a protective agent against MARF. We hypothesized that hyperbaric oxygen therapy (HBOT) may alleviate MARF by inducing renal HO-1 expression. Wistar-Albino rats were randomly assigned into three groups: Control (n = 4), MARF (n = 8), MARF + HBO (n = 8). MARF was induced by intramuscular glycerol (50%, 8 mL/kg) injection. Saline (8 mL/kg) was injected into the hind limb of the animals in the control group. Animals in the MARF + HBO group received two sessions of HBO therapy (90 min at 2.5 atm) 2 and 18 h after glycerol injection. Serum and tissue samples were taken at 24 h. Serum urea and creatinine levels increased in the MARF and MARF + HBO groups confirming the development of MARF. But, serum urea and creatinine levels were similar in MARF and MARF + HBO groups. Oxidative stress parameters were similar among all groups. Histological renal injury score was similar in MARF and MARF + HBO groups. HO-1 level, determined by immunohistochemistry, was significantly higher in MARF and MARF + HBO groups, compared to the control group. Although HO-1 level in MARF + HBO group was higher than MARF group, it was not statistically significant. We found that HBOT did not reduce renal injury in experimental MARF model. HBOT is used to reduce the muscle damage after crush injury, which may be accompanied by MARF. Therefore, more studies are needed to understand the effects of HBO treatment on renal functions after MARF.

We evaluated the feasibility of magnetic resonance imaging (MRI) for early detection of tubular injury by monitoring changes in the apparent diffusion coefficient (ADC) of renal water in a rat model of myohemoglobinuric glycerol-induced acute renal failure (ARF). Diffusion-weighted MRI was performed concurrently with measurements of serum creatinine and blood urea nitrogen (BUN), evaluation of renal perfusion with dynamic contrast-enhanced MRI, and renal morphological examination. ADC values in the cortex and outer medulla significantly declined within minutes after the glycerol administration (70-75% of control at 4 min and 50-60% of control at 15 min). Contrast-enhanced MRI demonstrated renal hypoperfusion at 20 min after the onset of injury. Light microscopy showed normal glomeruli and edematous tubular epithelial cells at 10 and 30 min, with more severe swelling and protein casts at 30 min. No changes in serum creatinine or BUN levels were detected. We hypothesize that decrease in renal ADC may be attributed to renal ischemia and to subsequent intracellular accumulation of diffusion-restricted water. Similar imaging evaluation in other experimental models of ARF, and in patients, will define the diagnostic value of renal ADC changes in early detection of acute tubular injury.

Two solid-phase radioimmunoassays have been developed for the detection of myoglobin in serum and urine. The sensitivity of the methods is 0.1 and 0.5 microgram/l, respectively, with a coefficient of variation of the respective method of 7-8%. The mean serum concentration of myoglobin in ninety-nine healthy blood donors was 44.3 microgram/l +/- 18.0 microgram/l (SD) with a significant difference (P less than 0.001) between men (50.6 +/- 19.8) and women (35.7 +/- 10.4). Serum myoglobin was positively correlated to age (P less than 0.05), body weight (P less than 0.02), serum creatine kinase (P less than 0.001), and serum creatinine (P less than 0.001) to galactose elimination rate. Serum myoglobin levels were not influenced by exhaustive short time dynamic exercise. The mean urinary excretion of myoglobin in twenty-four healthy students was 1.2 microgram/24 h (range 0.1-4 microgram/24 h). Myoglobin excretion was correlated to excretion of beta 2-microglobulin (P less than 0.02) but not to serum levels of myoglobin. No indications of circulating antibodies to myoglobin were obtained when assaying sixty-seven rheumatoid arthritis and thirteen myastenia gravis sera. Presence of other myoglobin binding substances in serum, which would interfere with the assays also seemed unlikely. Determination of myoglobin in serum by sensitive and specific method might be of clinical value in the diagnosis of diseases involving muscle tissues.