Effects Of Hydrogen Sulfide On The Gardos Channels Activity In Erythrocytes

Objective: The molecules of NO, H2S, CO formed in the body cells present a new group of intra- and intercellular mediators that may regulate a number of physiological functions. The targets of these molecules are often the proteins of ion channels. The aim of this research work was to study the effects of hydrogen sulfide (H2S) on the membrane potential of erythrocytes caused by activation of Ca2+ -dependent K+ channels (Gardos channels) in the presence of calcium ionophore or phenazinmetosulfate (PMS). Design and method: The study was performed on packed red blood cells obtained from the venous blood of twenty-four healthy male volunteers aged 20–27 years. The registration of the membrane potential of erythrocytes in the presence of Ca2+ -ionophore (A23187) or PMS was carried out by a potentiometric method. As an integral characteristic of Ca2+ -dependent K+ -permeability of erythrocytes membranes, the amplitude of the hyperpolarization response was calculated. Test compounds: sodium hydrosulfide (NaHS, 0.005, 0.01, 0.1, 0.2 mM), bumetanide (5 μM). Results: It was found that the addition of NaHS in concentrations of 0.005–0.2 mM to the medium incubated caused a change in the amplitude of the hyperpolarization response of the erythrocyte membrane caused by Ca2+ -ionophore (A23187) or PMS. In the presence of 0.005 mM NaHS the amplitude of the A23187-dependent response was significantly increased, while the amplitude of the PMS-dependent response was reduced. The suppression of A23187-dependent response in the presence of higher NaHS concentrations was more pronounced than the PMS-dependent one. The amplitude of the A23187-dependent response under the combined action of hydrogen sulphide and Na+, K+, 2Cl - cotransport (NKCC) blocker bumetanide increased and the PMS-dependent hyperpolarization response decreased in comparison with the absence of the blocker. Conclusions: This study showed that H2S has a modulating effect on the Gardos channels activity in erythrocyte membrane. Effects of H2S depend of the method of activation these channels. A23187-dependent response was more sensitive to H2S.