Oxygen Uptake of Canine Whole Body and Hind Limb with Hypocapnic Alkalosis

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Abstract
The effect of hypocapnic alkalosis induced by hyperventilation on whole-body and hind-limb O2 uptake (.ovrhdot.VO2) was studied in dogs anesthetized with pentobarbital. In the intact dog with a self-perfused hind limb, increasing pHa from 7.41-7.58 increased whole-body .ovrhdot.VO2 8% and decreased hind-limb .ovrhdot.VO2 6%. Isolated hind limbs perfused with heparinized whole blood had similar decreases in .ovrhdot.VO2 with increases in arterial blood pH (pHa). Isolated hind limbs perfused with whole blood containing citrate, phosphate and dextrose (CPD) showed muscle twitches, had larger .ovrhdot.VO2 values at identical pHa, and had an increase in .ovrhdot.VO2 with increase in pHa. These changes with a CPD perfusate were associated with low levels of ionized Ca (< 0.5 meq/l), disappeared when Ca ion spontaneously increased to 1.0 meq/l, and was prevented or abolished by the addition of calcium chloride, dantrolene, d-tubocurarine or succinylcholine. These results are in accord with the findings of others regarding an increase in whole-body .ovrhdot.VO2 with hypocapnic alkalosis, but do not support a contributory role of skeletal muscle to the overall increase.