Lactate provocation of panic attacks. II. Biochemical and physiological findings.

Thirty-one of 43 patients with panic disorder or agoraphobia with panic attacks and none of 20 normal controls panicked in response to infusions of sodium lactate. Before receiving lactate, patients showed higher heart rates than controls and also signs of hyperventilation. During lactate infusion, patients who did not panic, nevertheless, developed higher lactate and pyruvate levels and greater ionized calcium and pH changes than controls. Lactate-induced panic attacks were regularly accompanied by biological changes consistent with hyperventilation and central noradrenergic activation and irregularly by elevation of plasma norepinephrine and cortisol levels. Panic attacks were not associated with changes in epinephrine or calcium levels or pH. Baseline arousal increased the likelihood of panic during lactate infusion. It is hypothesized that lactate-induced panic primarily involves central noradrenergic discharge with inconsistent peripheral manifestations.