Failure of perfusion with oxygenated Krebs-Ringer solution to preserve the eccrine function of the vascular endothelium in bone.
An ex vivo canine tibia preparation was perfused at a constant rate with aerated (95% O2-5% CO2) Krebs-Ringer solution for 24 h. Bolus injections of norepinephrine (0.125-0.5 micrograms) were given and then acetylcholine (5 x 10(-5) M) was used to stimulate endothelial production of smooth muscle relaxing factors. Following 1 h of perfusion the addition of acetylcholine resulted in significant attenuation of the response to norepinephrine (p < 0.001). After 4 h perfusion acetylcholine did not attenuate the norepinephrine response, but addition of L-arginine (the precursor of endothelial-derived relaxing factor) resulted in significant attenuation in the presence of acetylcholine (p < 0.005). At 6, 12, and 24 h the acetylcholine did not attenuate the norepinephrine response. It is concluded that normothermic, continuous perfusion with oxygenated Krebs-Ringer solution results in normal endothelial eccrine activity up to 1 h. Following this period there is substrate depletion but endothelial eccrine function can be demonstrated for up to 4 h. At 6 h this function cannot be demonstrated, suggesting degradation of the functional integrity of the endothelium.
Moran
C G
CG
Department of Orthopedics, Mayo Clinic, Rochester, Minnesota 55905.
Wood
M B
MB
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001842:Bone and Bones / Q000098:blood supply*; D004285:Dogs; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D007552:Isotonic Solutions; D008833:Microcirculation; D009569:Nitric Oxide / Q000096:biosynthesis*; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D011453:Prostaglandins / Q000096:biosynthesis; D013977:Tibia; D014021:Tissue Preservation / Q000379:methods*
D007552:Isotonic Solutions; C051865:Krebs-Ringer solution; D011453:Prostaglandins; D009569:Nitric Oxide; D000109:Acetylcholine; D009638:Norepinephrine