Intravenous administration of sodium lactate in concentrations (0.5 M, 2 M) previously shown to elicit panic attacks in patients with panic disorder was found to cause a prompt and short-lasting increase in blood pressure in spontaneously hypertensive (SH) rats and in normotensive Wistar rats; in contrast, only weak and nonsignificant effects of lactate were observed in rats of the Sprague-Dawley strain. The effects of lactate on heart rate in SH rats varied; thus, whereas most rats displayed a modest bradycardia during lactate infusions, in some rats the increase in blood pressure was accompanied by an increase in heart rate. After pretreatment with antipanic medication [the serotonin and noradrenaline reuptake inhibitor clomipramine (10 mg/kg/day, 3 weeks) or the triazolobenzodiazepine alprazolam (2 mg/kg/day, 3 weeks)], the blood pressure response to sodium lactate in SH rats was significantly blunted; in contrast, acute pretreatment with clomipramine (10 mg/kg) did not reduce the response. It is suggested that further studies on the cardiovascular effects of sodium lactate in SH or Wistar rats may shed further light on the mechanisms underlying the panic-provoking effect of lactate in panic disorder patients and on the mode of action of antipanic drugs.

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Intravenous administration of sodium lactate in concentrations (0.5 M, 2 M) previously shown to elicit panic attacks in patients with panic disorder was found to cause a prompt and short-lasting increase in blood pressure in spontaneously hypertensive (SH) rats and in normotensive Wistar rats; in contrast, only weak and nonsignificant effects of lactate were observed in rats of the Sprague-Dawley strain. The effects of lactate on heart rate in SH rats varied; thus, whereas most rats displayed a modest bradycardia during lactate infusions, in some rats the increase in blood pressure was accompanied by an increase in heart rate. After pretreatment with