The effect of hypothermic ischemia on the alpha-adrenergic mechanisms of the canine tibia vascular bed.
The effect of hypothermic ischemia on alpha-1 and -2 adrenergic receptor mediated vasoconstriction has been studied in an in vitro perfused canine tibia preparation. Bones were perfused at a constant rate with aerated (95% O2, 5% CO2) modified Krebs Ringer solution and the effect of bolus injections of norepinephrine (0.025-6.4 nmol) on the perfusion pressure was studied. For all bones the first dose-response curve was produced under control conditions. In one group the second dose-response curve was generated during a constant infusion of prazosin (alpha-1 adrenergic antagonist); in another it was produced during a constant infusion of rauwolscine (alpha-2 adrenergic antagonist); in the control group it was generated under control conditions. The results demonstrate that, after 48 h of hypothermic ischemia, alpha-1 adrenergic-mediated vasoconstriction was significantly attenuated (p less than 0.001). However, alpha-2 adrenergic-mediated vasoconstriction was unaffected by increasing periods of hypothermic ischemia.
Davis
T R
TR
Department of Orthopedics, Mayo Clinic, Rochester, Minnesota 55905.
Wood
M B
MB
Vanhoutte
P M
PM
D000818:Animals; D001808:Blood Vessels / Q000294:innervation; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D007035:Hypothermia / Q000503:physiopathology*; D066298:In Vitro Techniques; D007511:Ischemia / Q000503:physiopathology*; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D011312:Pressure; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D012039:Regional Blood Flow; D013977:Tibia / Q000098:blood supply*; D015016:Yohimbine / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D009638:Norepinephrine