Intrinsic alteration of the reactive properties of arteries during hypothermia.
This study compares the reactive and contractile properties of helical strips of femoral arteries taken from normothermic rabbits and rabbits that were anesthetized with pentobarbital and cooled to 25 degrees C. The purpose of this comparison was to see if previous exposure to whole body hypothermia would alter vascular muscle responsiveness to norepinephrine. We found that, after 2 h of in vivo hypothermia, the hypothermic-derived vascular strips contracted more slowly, but required from 10 to 100 times less norepinephrine to have a detectable contractile response. This continued while the tissue was in vitro for at least 12 h. Although the maximal tension developed by the strips was equivalent, the ED50 values for the hypothermic-derived arteries were lower than those of the normothermic tissue. This study has identified prolonged alterations in in vitro vascular responsiveness attributable to previous exposure to whole body hypothermia, which may help to explain the disruptions of blood pressure during and following exposure of the whole body to cold.
Bandick
N R
NR
U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007.
Roberts
D E
DE
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D007035:Hypothermia / Q000503:physiopathology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
D009638:Norepinephrine