Effects of ischemia and hemoglobin on vascular function in isolated rabbit aortas.
The vascular endothelium is important in the modulation of vascular tone via production of endothelium-derived relaxing and contracting factors. The abdominal aortas of five groups of rabbits were subjected to varying lengths of ischemia (0, 1, 2, 3, or 4 hours), removed, sectioned into transverse rings, and placed in tissue baths containing Krebs' buffer at 37 degrees C and aerated with 95% O2/5% CO2. After equilibration the rings were tested for endothelium-dependent vasodilation with methacholine and nonendothelium-dependent vasodilation with nitroprusside. Endothelium-dependent relaxation as elicited by methacholine was impaired at 3 and 4 hours of ischemia but was not significantly different at 1 and 2 hours as compared to control, whereas endothelium-independent vasodilation remained normal throughout the different periods of ischemia. The addition of 1 x 10(-6) mol/L rabbit hemoglobin reduced the time needed to demonstrate significant impairment of endothelial function to 2 hours. Endothelium-independent vasodilation was not affected by hemoglobin. We conclude that hemoglobin exacerbates ischemia vascular dysfunction in the rabbit aorta.
Ruiz
A J
AJ
Department of Surgery, University of Virginia Health Sciences Center, Charlottesville 22908.
Chan
B B
BB
Meyerhoefer
T A
TA
Buck
D R
DR
Farley
P C
PC
Flanagan
T L
TL
Kron
I L
IL
D000818:Animals; D001012:Aorta, Abdominal / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D006454:Hemoglobins / Q000008:administration & dosage / Q000494:pharmacology*; D007511:Ischemia / Q000473:pathology / Q000503:physiopathology*; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000494:pharmacology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors*; D009599:Nitroprusside / Q000008:administration & dosage / Q000494:pharmacology; D011817:Rabbits; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D006454:Hemoglobins; D016210:Methacholine Chloride; D009599:Nitroprusside; D009569:Nitric Oxide