RESUMEN
<p><b>OBJECTIVE</b>To study the effects of extremely low frequency sinusoidal magnetic fields on hydrolysis of F(0)F(1)-ATPase and its mechanism.</p><p><b>METHODS</b>The F(0)F(1)-ATPases which was localized on the outer surface of chromatophores were prepared from the cells of Rhodospirillum rubrum and were exposed to 0.1 approximately 0.5 mT, 4.7 approximately 96.0 Hz magnetic fields.</p><p><b>RESULTS</b>The hydrolysis activity of F(0)F(1)-ATPase was stimulated by 0.5 mT, 4.7, 12.0, 60.0, 72.0, 84.0 and 96.0 Hz magnetic fields respectively and inhibited by 0.5 mT, 24.0 Hz magnetic field (P < 0.05); 0.3 mT, 4.7, 24.0 and 60.0 Hz magnetic fields also distinctly affected F(0)F(1)-ATPases activity respectively (P < 0.05), whereas 0.1 mT exposure caused no significant changes on that activity. When the hydrolysis activity of the F(0)F(1)-ATPases was inactivated by its inhibitor DCCD, the 0.5 mT, 24.0 Hz magnetic field still inhibited the hydrolysis activity of the F(0)F(1)-ATPase and 0.5 mT, 60.0 Hz magnetic field also had stimulating effects (P < 0.05).</p><p><b>CONCLUSION</b>The effects of magnetic fields on the hydrolysis activity of the F(0)F(1)-ATPases depend on not only magnetic frequency but also magnetic intensity. The threshold of magnetic intensity is between 0.1 mT and 0.3 mT. F(0)F(1)-ATPases, especially F1-portion may be an end-point of magnetic fields.</p>