Changes in blood pressure and heart rate by repetitive transcranial magnetic stimulation in rats

We examined whether repetitive transcranial magnetic stimulation (rTMS) could influence blood pressure (BP) and heart rate (HR) in rats and the possible mechanisms involved. In urethane anesthetized Wistar-Kyoto rats, BP and HR were recorded from the femoral artery around the point of rTMS at a frequency of 10 Hz and an intensity of 1.88-2.44 Tesla. rTMS but not sham stimulation reduced BP and HR by approximately 20 mmHg and approximately 30 beats/min, respectively (n = 22). Pretreatment with an alpha-adrenoceptor antagonist, prazosin, or a beta-adrenoceptor antagonist, atenolol, significantly attenuated the response, whereas the muscarinic acetylcholine antagonist, atropine, had little effect. An inhibitory effect of prazosin on BP reduction by rTMS was also observed when basal BP was preserved by a combination of prazosin and a nitric oxide synthase inhibitor, N-monomethyl-L-arginine. These results suggest that rTMS reduces BP through the inhibition of the sympathetic nervous system but not through activation of the parasympathetic nervous system.