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Modulatory effects of static magnetic fields on blood pressure in rabbits
Author(s) -
Okano Hideyuki,
Ohkubo Chiyoji
Publication year - 2001
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.68
Subject(s) - nicardipine , vasodilation , vasoconstriction , blood pressure , vasomotion , medicine , plethysmograph , hemodynamics , artery , nitric oxide synthase , anesthesia , endocrinology , nitric oxide , chemistry , pharmacology
Acute effects of locally applied static magnetic fields (SMF) on pharmacologically altered blood pressure (BP) in a central artery of the ear lobe of a conscious rabbit were evaluated. Hypotensive and vasodilator actions were induced by a Ca 2+ channel blocker, nicardipine (NIC). Hypertensive and vasoconstrictive actions were induced by a nitric oxide synthase (NOS) inhibitor, N ω ‐nitro‐ L ‐arginine methyl ester (L‐NAME). The hemodynamic changes in the artery exposed to SMF were measured continuously and analyzed by penetrating microphotoelectric plethysmography (MPPG). Concurrently, BP changes in a central artery contralateral to that of the exposed ear lobe were monitored. SMF intensity was 1 mT and the duration of exposure was 30 min. A total of 180 experimental trials were carried out in 34 healthy adult male rabbits weighing 2.6–3.8 kg. Six experimental procedures were chosen at random: (1) sham exposure without pharmacological treatment; (2) SMF exposure alone; (3) decreased BP induced by a single intravenous (iv) bolus injection of NIC (100 μM/kg) without SMF exposure; (4) decreased BP induced by injection of NIC with SMF exposure; (5) increased BP induced by a constant iv infusion of L‐NAME (10 mM/kg/h) without SMF exposure; (6) increased BP induced by infusion of L‐NAME with SMF exposure. The results demonstrated that SMF significantly reduced the vasodilatation with enhanced vasomotion and antagonized the reduction of BP via NIC‐blocked Ca 2+ channels in vascular smooth muscle cells. In addition, SMF significantly attenuated the vasoconstriction and suppressed the elevation of BP via NOS inhibition in vascular endothelial cells and/or central nervous system neurons. These results suggest that these modulatory effects of SMF on BP might, in part, involve a feedback control system for alteration in NOS activity in conjunction with modulation of Ca 2+ dynamics. Bioelectromagnetics 22:408–418, 2001. © 2001 Wiley‐Liss, Inc.