Effect of cold on ischemia-reperfusion-induced microvascular permeability increase in cat skeletal muscle

Abstract

The effects of reduced temperature during ischemia (I) upon micro vascular permeability and resistance increases during reperfusion (R) were assessed in skeletal muscle. Protein solvent-drag reflection coefficients (σf) 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. σfwas 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 σf. However, when the ischemia was at ∼5°C, there was a significant fall in σfto ∼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. © 1994 by Academic Press, Inc.