The effect of modulation of hydrogen peroxide, nitric oxide and hydrogen sulfide on contractile reactions of smooth muscle cells caused by depolarization, phenylephrine and solutions with altered osmolarity has been investigated by the mechanographical method. The new data of the fundamental nature of the role of reactive oxygen species in the operation of calcium and cGMP-mediated intracellular signaling systems, as well as in volume-dependent regulation of smooth muscle contraction.