Anti-pressor effects of whole body exposure to static magnetic field on pharmacologically induced hypertension in conscious rabbits.
Acute effects of whole body exposure to static magnetic field (SMF) on pharmacologically induced hypertension in a conscious rabbit were evaluated. Hypertensive and vasoconstrictive actions were induced by norepinephrine (NE) or a nonselective nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-l-arginine methyl ester (l-NAME). The hemodynamics in a central artery of the ear lobe was measured continuously and analyzed by penetrating microphotoelectric plethysmography (MPPG). Concurrently, blood pressure (BP) changes in a central artery, contralateral to that of the MPPG measured ear lobe, were monitored. Magnetic flux densities were 5.5 mT (Bmax), the magnetic gradient peaked in the throat at the level of approximately 0.09 mT/mm, and the duration of exposure was 30 min. The results demonstrated that under normal physiological conditions without treatment of pharmacological agents, there were no statistically significant differences in the hemodynamics and BP changes between the sham and the SMF exposure alone. Under pharmacologically induced hypertensive conditions, the whole body exposure to nonuniform SMF with peak magnetic gradient in the carotid sinus baroreceptor significantly attenuated the vasoconstriction and suppressed the elevation of BPs. These findings suggest that antipressor effects of the SMF on the hemodynamics under NE or l-NAME induced high vascular tone might be, in part, dependent on modulation of NE mediated response in conjunction with alteration in NOS activity, thereby modulating BPs.
Okano
Hideyuki
H
Department of Environmental Health, National Institute of Public Health, Tokyo, Japan. okano@niph.go.jp
Ohkubo
Chiyoji
C
D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000503:physiopathology / Q000528:radiation effects*; D001794:Blood Pressure / Q000187:drug effects / Q000528:radiation effects*; D004423:Ear / Q000098:blood supply; D004574:Electromagnetic Fields; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology* / Q000532:radiotherapy; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine; D010991:Plethysmography / Q000379:methods; D011817:Rabbits; D012016:Reference Values; D014661:Vasoconstriction / Q000187:drug effects / Q000528:radiation effects; D014916:Whole-Body Irradiation / Q000379:methods*
D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine