Difference between revisions of "Gorbacheva 2013 Abstract MiP2013"
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It is known that mitochondrial ATP-dependent channel (mtKATP), plays a key role in protecting the myocardium during ischemia [1]. In our laboratory it was shown that the stimulation of mtKATP activates the output potassium system in mitochondria in exchange for protons. The activation of this cycle should lead to mild uncoupling, indicated by a slight decrease in membrane potential. Reduced potential on the inner mt-membrane by 10% leads to a decrease in the formation of peroxides by 70% [2]. A possible result of active cyclization of potassium in mitochondria, in our opinion, is the reduction in oxidative stress and, consequently, the recovery of the energy balance in the ischemic myocardium. To record cyclization of potassium in the mitochondria, we used a spectrophotometric method. Log potassium ions was determined by the rate of swelling of mitochondria in hypotonic medium. The kinetics of swelling was recorded by changing the optical density of the suspension of mitochondria at a wavelength of 520 nm for 30-40 min. The swelling rate was calculated from the change in light scattering per unit time. Under these conditions, there was swelling and shrinking of organelles that was manifested in the form of two or three waves. This probably reflects synchronized input and output of potassium in some organelles. The study of the influence of the degree of coupling of mitochondria in the cyclization of potassium showed that over time the oxidation of free organelles increases and respiratory control was reduced. Thus, the cyclization of potassium in mitochondria depends on their coupling. We studied the influence of modulators of mtKATP on the system cyclization of potassium in the mitochondria to determine whether the channel is involved in the observed fluctuations of the potassium ion. The addition of ATP-Mg2+ at physiological concentration of 1 mM led to a decrease in the rate of swelling of organelles reflecting volatile input potassium ion. When 5 mM of 4-aminopyridine was added to the incubation medium of mitochondrial suspensions, a swelling-inhibiting effect was observed as with the addition of ATP. One of the activators of the mtKATP channel is ADP. In our experiments 500 µM ADP activates entry of potassium ions into the mitochondria by 85%. It is known that sildenafil exhibits cardioprotective effects on the whole organism, and a specific inhibitor of mtKATP 5-hydroxydecanoate removes this effect [3]. We made the assumption that sildenafil has an impact on mtKATP, being its activator. We found that sildenafil in concentration of 125 µM accelerates the entry of potassium ions into the mitochondria of rat liver by 30-40%, and also partially removes the inhibitory effect of ATP-Mg2+. Thus, the cardioprotective effect of sildenafil may be associated with activation of the mtKATP channel. | It is known that mitochondrial ATP-dependent channel (mtKATP), plays a key role in protecting the myocardium during ischemia [1]. In our laboratory it was shown that the stimulation of mtKATP activates the output potassium system in mitochondria in exchange for protons. The activation of this cycle should lead to mild uncoupling, indicated by a slight decrease in membrane potential. Reduced potential on the inner mt-membrane by 10% leads to a decrease in the formation of peroxides by 70% [2]. A possible result of active cyclization of potassium in mitochondria, in our opinion, is the reduction in oxidative stress and, consequently, the recovery of the energy balance in the ischemic myocardium. To record cyclization of potassium in the mitochondria, we used a spectrophotometric method. Log potassium ions was determined by the rate of swelling of mitochondria in hypotonic medium. The kinetics of swelling was recorded by changing the optical density of the suspension of mitochondria at a wavelength of 520 nm for 30-40 min. The swelling rate was calculated from the change in light scattering per unit time. Under these conditions, there was swelling and shrinking of organelles that was manifested in the form of two or three waves. This probably reflects synchronized input and output of potassium in some organelles. The study of the influence of the degree of coupling of mitochondria in the cyclization of potassium showed that over time the oxidation of free organelles increases and respiratory control was reduced. Thus, the cyclization of potassium in mitochondria depends on their coupling. We studied the influence of modulators of mtKATP on the system cyclization of potassium in the mitochondria to determine whether the channel is involved in the observed fluctuations of the potassium ion. The addition of ATP-Mg2+ at physiological concentration of 1 mM led to a decrease in the rate of swelling of organelles reflecting volatile input potassium ion. When 5 mM of 4-aminopyridine was added to the incubation medium of mitochondrial suspensions, a swelling-inhibiting effect was observed as with the addition of ATP. One of the activators of the mtKATP channel is ADP. In our experiments 500 µM ADP activates entry of potassium ions into the mitochondria by 85%. It is known that sildenafil exhibits cardioprotective effects on the whole organism, and a specific inhibitor of mtKATP 5-hydroxydecanoate removes this effect [3]. We made the assumption that sildenafil has an impact on mtKATP, being its activator. We found that sildenafil in concentration of 125 µM accelerates the entry of potassium ions into the mitochondria of rat liver by 30-40%, and also partially removes the inhibitory effect of ATP-Mg2+. Thus, the cardioprotective effect of sildenafil may be associated with activation of the mtKATP channel. | ||
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Revision as of 15:19, 13 August 2013
| Gorbacheva O, Venediktova NI, Moshkov DA, Mironova GD (2013) Cyclization of potassium in rat liver mitochondria in the function of the mitochondrial ATP-dependent potassium channel. Its possible role in cardioprotection. Mitochondr Physiol Network 18.08. |
Link:
Gorbacheva O, Venediktova NI, Moshkov DA, Mironova GD (2013)
Event: MiP2013
It is known that mitochondrial ATP-dependent channel (mtKATP), plays a key role in protecting the myocardium during ischemia [1]. In our laboratory it was shown that the stimulation of mtKATP activates the output potassium system in mitochondria in exchange for protons. The activation of this cycle should lead to mild uncoupling, indicated by a slight decrease in membrane potential. Reduced potential on the inner mt-membrane by 10% leads to a decrease in the formation of peroxides by 70% [2]. A possible result of active cyclization of potassium in mitochondria, in our opinion, is the reduction in oxidative stress and, consequently, the recovery of the energy balance in the ischemic myocardium. To record cyclization of potassium in the mitochondria, we used a spectrophotometric method. Log potassium ions was determined by the rate of swelling of mitochondria in hypotonic medium. The kinetics of swelling was recorded by changing the optical density of the suspension of mitochondria at a wavelength of 520 nm for 30-40 min. The swelling rate was calculated from the change in light scattering per unit time. Under these conditions, there was swelling and shrinking of organelles that was manifested in the form of two or three waves. This probably reflects synchronized input and output of potassium in some organelles. The study of the influence of the degree of coupling of mitochondria in the cyclization of potassium showed that over time the oxidation of free organelles increases and respiratory control was reduced. Thus, the cyclization of potassium in mitochondria depends on their coupling. We studied the influence of modulators of mtKATP on the system cyclization of potassium in the mitochondria to determine whether the channel is involved in the observed fluctuations of the potassium ion. The addition of ATP-Mg2+ at physiological concentration of 1 mM led to a decrease in the rate of swelling of organelles reflecting volatile input potassium ion. When 5 mM of 4-aminopyridine was added to the incubation medium of mitochondrial suspensions, a swelling-inhibiting effect was observed as with the addition of ATP. One of the activators of the mtKATP channel is ADP. In our experiments 500 µM ADP activates entry of potassium ions into the mitochondria by 85%. It is known that sildenafil exhibits cardioprotective effects on the whole organism, and a specific inhibitor of mtKATP 5-hydroxydecanoate removes this effect [3]. We made the assumption that sildenafil has an impact on mtKATP, being its activator. We found that sildenafil in concentration of 125 µM accelerates the entry of potassium ions into the mitochondria of rat liver by 30-40%, and also partially removes the inhibitory effect of ATP-Mg2+. Thus, the cardioprotective effect of sildenafil may be associated with activation of the mtKATP channel.
Labels:
Prep2
Affiliations and author contributions
1 - Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Russia;
2 - Pushchino State University, Pushchino, Russia.
Email: [email protected]
Supported by RFBR №10-04-00920-a; DPNNiT №4.3010.2011, RFBR №12-04-32187-mol_a.
References
- Garlid K, Paucek P, Yarov-Yarovoy V, Murray H, Darbenzio R, D'Alonzo A, Lodge N, Smith M, Grover G (1997) Cardioprotective effect of diazoxide and its interaction with mitochondrial ATP-sensitive K+ channels. Possible mechanism of cardioprotection. Circ Res 81: 1072-1082.
- Korshunov SS, Skulachev VP, Starkov AA (1997) High protonic potential actuates a mechanism of production of reactive oxygen species in mitochondria. FEBS Lett 416: 15-18.
- Ockaili R, Salloum F, Hawkins J, Kukreja R (2002) Sildenafil (Viagra) induces powerful cardioprotective effect via opening of mitochondrial KATP channels in rabbits. Am J Physiol Heart Circ Physiol 283: 1263-1269.
