Effects of oxygen and flow on the diameter of the femoral artery of the rabbit.

Contradictory results concerning the effects of oxygen and flow on blood vessel dimensions have been published. The aim of this study was to investigate the diameter changes in isolated, cannulated femoral arteries (n = 5) of the rabbit in a preconstricted state (two norepinephrine levels) during high and low pO2 (both inside and outside) at different flow levels. In this way the interaction between oxygen and flow is also investigated. Results were normalized to relative diameters, where the diameter at zero flow, during high pO2 and low norepinephrine concentration was considered as a control diameter (100%). We found three effects in this study: (1) going from high to low oxygen, there was a global vasoconstriction (repeated measures, analysis of variance, p = 0.016 with low norepinephrine and p = 0.015 with high norepinephrine); (2) when flow was increased from 1 to 100 ml/h, we found a significant (p less than 0.001) flow-dependent constriction under all four conditions, and (3) there is an interaction between flow and oxygen, for example at low norepinephrine the constriction due to low oxygen is 16% at zero flow and 1% at a flow of 1 ml/h, at high norepinephrine these numbers are 22 and 10%, respectively.