Figure 6. Covering aparenchymal segments with glass and occluding them to eliminate blood flow does not eliminate arteriolar O₂ reactivity .

A, schematic diagram of an aparenchymal segment in which the parenchyma has been removed from a long segment of hamster cheek pouch arteriole as described by Jackson & Duling (1983). Elevation of the $P_{{\mathrm{O}}_2}$ of the solution flowing over the preparation from 12 to 150 mmHg resulted in arteriolar constriction as depicted in D. As shown in B, subsequent covering of the aparenchymal segment with a piece of glass coverslip (sealed in place with silicone grease), to eliminate contact of the arteriole with the superfusate, had no effect on O₂‐induced constriction as shown in D. To eliminate blood flow through the covered aparenchymal segments, an occluding pipette was used as shown in C. Despite the lack of access to the superfusate and flowing blood, these covered and occluded aparenchymal segments retained significant O₂ reactivity as shown in D. These data suggest that the constriction induced by elevated $P_{{\mathrm{O}}_2}$ can be conducted along the arteriolar wall. See Jackson & Duling (1983) for details.