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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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THE NEPHROTOXICITY RISK IN RATS SUBJECTED TO HEAVY MUSCLE ACTIVITY |
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Gülsen Öner 
and Selma Cirrik |
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Akdeniz University, Medical Faculty, Department of Physiology, Antalya, Turkey. |
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© Journal of Sports Science and Medicine (2009) 8, 481 - 488 |
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| ABSTRACT | |||
| When the body is exposed to insults, the kidneys exhibit adaptive
changes termed renal cytoresistance, characterized by cholesterol accumulation
in the membranes of the tubule cells. However, heavy muscle activity has
not yet been accepted as one of the stressors that could lead to cytoresistance.
In order to study the renal functional characteristics of animals exposed
to heavy muscle activity, rats were subjected to exhaustive treadmill exercise
for 5 days and their data was compared to those of sedentary controls. It
was found that in exercised rats, blood lactate, muscle citrate synthase
and proximal tubule peroxynitrite levels were all elevated, suggesting the
presence of oxidative stress in the proximal tubule segments. However, mean
arterial pressure, renal blood flow, glomerular filtration rate, fractional
excretion of sodium and potassium, and organic anion excretion remained
normal. Despite unchanged blood cholesterol levels, cholesterol loading
in the proximal tubule segments, especially the free form, and decreased
lactate dehydrogenase release from cytoresistant proximal tubule segments
indicated the development of renal cytoresistance. However, this resistance
did not seem to have protected the kidneys as expected because organic anion
accumulation associated with glycosuria and proteinuria, in addition to
the elevated urinary cholesterol levels, all imply the presence of an impaired
glomerular permeability and reabsorption in the proximal tubule cells. Therefore,
we suggest that in response to heavy muscle activity the tubular secretion
may remain intact, although cytoresistance in the proximal tubule cells
may affect the tubular reabsorptive functions and basolateral uptake of
substances. Thus, this differential sensitivity in the cytoresistance should
be taken into account during functional evaluation of the kidneys. Key words: Exercise, proximal tubule, cytoresistance, nephrotoxicity. |
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