Carbicarb is a mixture of Na2CO3/NaHCO3 that buffers similarly to NaHCO3, but without net generation of CO2. We studied the effects of carbicarb in an animal preparation of hypoxic lactic acidosis (HLA). HLA was induced by ventilating dogs with an hypoxic gas mixture (8% O2/92% N2). Dogs with HLA (n = 28) were then treated with 2.5 meq/kg of either NaHCO3 or carbicarb over 1 hr. Measurements were made, after 1 hr of hypoxia and 1 hr of therapy, of: cardiac hemodynamics, blood gases, liver intracellular pH (pHi), oxygen consumption, and regional lactate production. After therapy, the arterial pH rose with carbicarb (7.22 to 7.27, p less than .01), and fell with NaHCO3 (7.18 to 7.13, p less than .01). Mixed venous PCO2 did not change with carbicarb but increased with NaHCO3 (p less than .05). Arterial lactates stabilized with carbicarb but rose with NaHCO3 (by 3.1 mmol/liter, p less than .005). Lactate use by muscle, gut, and liver all improved with carbicarb and decreased with NaHCO3. The liver pHi (normal = 6.99, hypoxia = 6.80) improved with carbicarb (to 6.92), but decreased further with NaHCO3 (to 6.40). Muscle O2 consumption rose with carbicarb, whereas it decreased with NaHCO3. Arterial pressure fell less with carbicarb (-12 vs -46 mm Hg, p less than .006) and the cardiac output was stable with carbicarb but decreased with NaHCO3 (from 143 to 98 ml/kg/min, p less than .004). Stroke volume also improved with carbicarb but there was no change in pulmonary capillary wedge pressure, suggesting that carbicarb had a beneficial effect on myocardial contractility.(ABSTRACT TRUNCATED AT 250 WORDS)