Figure 2.

Typical tracing for the actions of 12-phenylacetate 13-acetate 20-homovanillate (PPAHV; 0.2 μM) on venous PO₂ and perfusion pressure (PP) in the perfused rat hindlimb. The first infusion of PPAHV caused a strong reduction in venous PO₂ (and hence stimulation of VO₂) and a mild increase in hindlimb PP reflecting a vasoconstrictor effect. Removal of PPAHV resulted in the return of venous PO₂ and PP to basal levels. With subsequent infusion of the same concentrations of PPAHV, the effect on venous PO₂ was markedly reduced while that for PP was enhanced.