Fig. 3.

Average rates of nitrite consumption in vitro during first 10 min incubation by homogenates of sanguinous (A) or asanguinous (B) rat heart incubated with 2,000 nmol/l sodium nitrite under conditions listed. Deoxygenating the incubation medium to Po₂ of 18 ± 3 mmHg (Deoxy, black bars) accelerated nitrite consumption by sanguinous heart tissue, whereas acidifying it accelerated nitrite consumption by asanguinous tissue, and 40% of the acidification effect could be blocked by allopurinol. Deoxygenating the medium further to Po₂ of 8 ± 1 mmHg (Deoxy-2, gray bars) accelerated acidic nitrite consumption still further in both sanguinous and asanguinous assays. *P < 0.05 vs. De-Oxy (pH 7.4); ¶P < 0.05 vs. De-Oxy (pH 5.5).