Effects of reduced oxygen tension on endothelium-dependent relaxation induced by acetylcholine differ in rabbit femoral artery and jugular vein.
In intact rabbit femoral artery rings pre-contracted with phenylephrine, acetylcholine (ACh; 10(-9)-10(-6) M) produces endothelium-dependent relaxation, abolished after mechanical rubbing to remove the endothelium. The response to ACh was absent at low oxygen tension (less than or equal to 4 kPa) or in the presence of sodium cyanide (1 mM). Intact rabbit jugular veins relaxed to ACh in lower concentration than did the femoral artery, 10(-10)-10(-8) M; at sufficient ACh concentration the relaxation was complete. In veins with completely removed endothelium no relaxation to ACh occurred, and at concentrations above 3 x 10(-7) M the response was a contraction. The relaxation response to ACh of intact veins persisted during contraction at lower oxygen tension or in the presence of 1 mM sodium cyanide. In rubbed veins, cyanide consistently induced a transient contraction, which was absent in intact veins. The study demonstrates pronounced endothelium-dependent relaxation to ACh in a venous preparation, with a markedly lower sensitivity of the relaxation response to hypoxia than in a muscular artery of the same species.
Vedernikov
Y P
YP
Department of Physiology and Biophysics, University of Lund, Sweden.
Hellstrand
P
P
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D004730:Endothelium, Vascular / Q000187:drug effects*; D005263:Femoral Artery / Q000187:drug effects*; D007601:Jugular Veins / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010100:Oxygen / Q000032:analysis; D011817:Rabbits; D014655:Vascular Resistance / Q000187:drug effects
D000109:Acetylcholine; D010100:Oxygen