Effects of sodium lactate infusion on cisternal lactate and carbon dioxide levels in nonhuman primates

Objective: To further the understanding of lactate-induced panic in patients with panic disorder, the authors examined cisternal lactate and carbon dioxide levels in nonhuman primates after infusions of sodium lactate comparable to those used in studies of human beings. Method: CSF and venous blood lactate, pH, PCO₂, PO₂, and bicarbonate were measured in five ketamine-anesthetized nonhuman primates, without mechanical ventilation, before and after they underwent infusions of sodium lactate. In addition, the same measurements were made for three of the five subjects who were given saline infusions. Results: Despite the development of the characteristic peripheral biochemical effects of infused sodium lactate - increased lactate and bicarbonate levels and metabolic alkalosis - no increases in central lactate or carbon dioxide levels were observed. Saline infusions produced no biochemical effects on venous and cisternal measures. Conclusions: The results of this study are in keeping with previous findings of nonpermeability of the blood-brain barrier to anionic compounds such as lactate. They therefore support theories of lactate panic based on cognitive and/or brainstem misevaluation of peripheral somatic sensations.