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Antioxidants Found to Alter Muscle Oxygen Use in Rats

Study finds oxygen delivery and consumption altered in resting and contracting muscle

MONDAY, Feb. 1 (HealthDay News) -- Antioxidants alter the pattern of oxygen delivery and consumption in resting and contracting muscle in aged rats, according to recent studies at Kansas State University, including research originally published in the December 2008 issue of the Journal of Applied Physiology.

Kyle F. Herspring, of Kansas State University in Manhattan, and colleagues examined the effect of intravenous antioxidants (tempol and ascorbic acid) on muscle microvascular oxygen partial pressure (PmvO2) and muscle blood flow in aged male rats at rest and during contractions of the spinotrapezius muscle.

The researchers found that, in resting muscle, antioxidants significantly increased the baseline PmvO2 without affecting muscle blood flow. In contracting muscle, antioxidants reduced or abolished the "undershoot" in the biphasic PmvO2 changes normally observed during contractions before reaching the steady state value, while significantly reducing muscle blood flow during steady-state contractions. In addition, antioxidants were found to significantly impair muscle force production during contractions.

"The antioxidant and pro-oxidant balance is really delicate. One of the things we've seen in our research is that you can't just give a larger dose of antioxidants and presume that there will be some sort of beneficial effect. In fact, you can actually make a problem worse," co-authors of the study said in a recent press release. "It's really a cautionary note that, before we start recommending people get more antioxidants, we need to understand more about how they function in physiological systems and circumstances like exercise."

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