Abstract
The effects of reduced temperature during ischemia (I) upon microvascular permeability and resistance increases during reperfusion (R) were assessed in skeletal muscle. Protein solvent-drag reflection coefficients (σ f) and changes in vascular resistance were measured during 37°C reperfusion of isolated, whole-blood perfused cat bindlimbs after the limbs had been subjected to 3.5 h of ischemia at several temperatures. σ f was determined from the disappearance rates of water and protein from the circulating perfusate during a period of induced microvascular fluid filtration. The I/R procedure at 37°C caused σf to fall from ∼0.85 to ∼0.5, indicating a large increase in microvascular permeability. Hypothermic ischemia at 30, 22, 17, or 12°C totally abolished this drop in σ f. However, when the ischemia was at ∼5°C, there was a significant fall in σ f to ∼0.7, which was similar to the value we found previously with 5 h of continuous perfusion at this low temperature. The normothermic I/R procedure led to an increase in vascular resistance of ∼250% above the value measured prior to I/R. Hypothermic ischemia totally abolished this resistance increase, except for the lowest temperature, for which the increase was 150%. Therefore, hypothermia can prevent the microvascular dysfunction caused by 3.5 b of ischemia at 37°C in this preparation. However, when the temperature was reduced too far (∼5°C), a cold injury to the microvascular resulted in permeability and resistance increases.
Published Version
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