Figure 5. Perfusion of arterioles in situ with solutions equilibrated with high ${\mathit{}\mathit{P}}_{{\mathit{}\mathrm{O}}_{\mathit{}2}}$ has no effect on arteriolar tone .

A and B are reproduced from Jackson (1987). A, schematic diagram of a hamster cheek pouch arteriole in which a sharpened fluid‐filled pipette has been inserted through the wall of an arteriole allowing perfusion of the arteriole with PSS equilibrated with varied $P_{{\mathrm{O}}_2}$. The entire cheek pouch preparation was superfused with PSS to allow global changes in $P_{{\mathrm{O}}_2}$. B, summary data (means ± SEM). Perfusion of the arterioles with solutions equilibrated with high or low $P_{{\mathrm{O}}_2}$ had no significant effect on arteriolar diameter. Only when the global $P_{{\mathrm{O}}_2}$ was elevated via the superfusate did the arterioles constrict (compare low $P_{{\mathrm{O}}_2}$ superfusate points with high $P_{{\mathrm{O}}_2}$ superfusate points). These data suggest that components of the arteriolar wall (endothelial cells, smooth muscle cells or perivascular nerves) are not the sensor cells responsible for arteriolar O₂ reactivity in the hamster cheek pouch. See Jackson (1987) for details.