Arteriolar and venular reactivity to superfusate pO2 in tissues with different metabolic capacity. A study in skeletal muscle and mesentery of the rat.
In skeletal muscle (extensor hallucis proprius) and mesentery of anesthetised (pentobarbital 30 mg/kg) female rats (200 g) we have compared reactivity to O2 of arterioles and venules with their response to a vasoconstrictor (epinephrine 5.5 x 10(-7) M) and a vasodilator (adenosine 10(-4) M). Muscle arterioles fully constricted with O2 and epinephrine and dilated with adenosine (22%). Muscle venules did not respond to changes in superfusate pO2, constricted 18% with epinephrine and dilated 10% with adenosine. In the mesentery changes in superfusate pO2 had no effect on diameters of arterioles or venules but epinephrine fully constricted arterioles and constricted venules by 19%, while adenosine dilated arterioles (6%) but not venules. When we set arteriolar and venular diameters during adenosine superfusion at 100%, muscle arterioles appeared to operate at 63% and mesenterial arterioles at 84% of maximal diameter at normal tissue pO2. For venules these percentages were 91 and 97%, respectively. Arterioles and venules in muscle thus have higher tone and muscle arterioles are greatly sensitive to changes in tissue pO2 while in our preparation mesenterial arterioles are not.
Van den Bos
G C
GC
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
Westerhof
N
N
Hoogerwerf
N
N
Sicking
A H
AH
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D001160:Arterioles / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000378:metabolism; D008642:Mesenteric Veins / Q000187:drug effects* / Q000378:metabolism; D008833:Microcirculation; D009132:Muscles / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D010313:Partial Pressure; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D014699:Venules / Q000187:drug effects
D000241:Adenosine; D010100:Oxygen; D004837:Epinephrine