Key result
Fractionated X irradiation of the mouse limb significantly increased resting blood flow clearance but caused a progressive inability to undergo reactive hyperemia following temporary ischemia.
Fractionated X irradiation causes progressive impairment of reactive hyperemia in mouse limbs, which correlates with the development of late tissue necrosis.
Suggests radiation may impair microvascular reactivity in limbs; hypothesis-generating for late necrosis mechanisms and needs human validation.
The right hind limbs of male C3H mice were treated with fractionated irradiation to total doses of 4,000–7,000 rads. Estimates of mean limb blood flow were obtained from the control and irradiated limb under both resting and tourniquet-induced hyperemic conditions at intervals of up to 30 weeks postirradiation by measuring the rate of clearance of inhaled xenon-133. Under resting conditions, the irradiated limbs showed a significantly increased clearance rate. However, following temporary ischemia, a marked, progressively developing inability of the irradiated limb to undergo reactive hyperemia was found. A correlation of this change with the progressively developing late necrosis of the leg was noted.
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Horn et al. (1974) studied this question. Fractionated X irradiation vs. Control limb was evaluated on Mean limb blood flow (clearance rate of inhaled xenon-133). Fractionated X irradiation of the mouse limb significantly increased resting blood flow clearance but caused a progressive inability to undergo reactive hyperemia following temporary ischemia.