title: Changes of blood lactate levels after repetitive transcranial magnetic stimulation.
abstract: The objective was to study whether repetitive transcranial magnetic stimulation (rTMS) of the motor cortex could induce modification of peripheral blood lactate values. Nineteen young healthy volunteers were included; during the study, all subjects were at rest, sitting on a comfortable armchair. The muscular activation was evaluated by continuous electromyographic record. TMS was performed by using a circular coil at the vertex. Resting motor threshold (rMT) was defined as the lowest TMS intensity able to induce motor responses of an amplitude >50 microV in the relaxed contralateral target muscle in approximately 50% of 20 consecutive stimuli. Venous blood lactate values were measured before, immediately after and 10 min after a single session of low frequencies (1Hz for 15 min) rTMS (LF rTMS) or high frequency (20 Hz for 15 min) rTMS (HF rTMS). As expected, LF rTMS induced a decrease of motor cortex excitability, whereas HF rTMS evoked an increase of motor cortex excitability. However, in the present investigation we observed that both conditions are associated to a significant increase of blood lactate. Since in our experimental conditions we can exclude a muscular production of lactate, the significant increment of peripheral blood lactate values, observed 10 min after the end of the rTMS session, is probably due to the crossing by brain-produced lactate of the blood-brain barrier.
authors.affiliation: Unità Operativa di Neurologia, Azienda Ospedaliera Cannizzaro, Catania, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Alagona
authors.forename: Marinella
authors.initials: M
authors.lastname: Coco
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rapisarda
authors.forename: Erminio
authors.initials: E
authors.lastname: Costanzo
authors.forename: Tiziana
authors.initials: T
authors.lastname: Maci
authors.forename: Domenico
authors.initials: D
authors.lastname: Restivo
authors.forename: Antonino
authors.initials: A
authors.lastname: Maugeri
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Perciavalle
mesh_terms: D000328:Adult; D001703:Biophysics; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009044:Motor Cortex / Q000502:physiology* / Q000528:radiation effects*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
chemical_list: D019344:Lactic Acid