| 2884664 |
Fry CH, Harding DP, Mounsey JP: The effects of cyanide on intracellular ionic exchange in ferret and rat ventricular myocardium. Proc R Soc Lond B Biol Sci. 1987 Feb 23;230(1258):53-75.
The effects of cyanide on Ca2+ exchange in isolated ventricular myocytes and on the intracellular concentrations of Ca2+, Na+ and H+ have been investigated to assess the contribution that mitochondria might play in cellular Ca2+ metabolism. Ionic levels were measured with ion-selective electrodes. KCN (2.5 mM) inhibited a component of Ca2+ exchange in myocytes that could be attributed to mitochondrial exchange, but was without effect on non-mitochondrial Ca2+ exchange. NaCN (2.5 mM) caused a transient reduction of [H+] i, [Na+] i and [Ca2+] i when applied to the superfusate bathing ventricular trabeculae or papillary muscles. The transient changes of [Na+] i were accentuated when the preparation was exposed to a solution which would be expected to increase the cellular calcium content. The reduction of [Na+] i which accompanies a reduction of the extracellular sodium concentration, [Na] o, was attenuated in the presence of NaCN, but the intracellular acidosis resulting from a reduction of [Na] o was unaffected by NaCN. A small, but significant, rise of [Ca2+] i accompanied a reduction of [Na] o but only when NaCN was present in the superfusate. It is concluded that cyanide ions have a reasonably specific action on cardiac cellular ionic metabolism. Its primary action is to prevent mitochondrial Ca2+ sequestration. It is postulated that a Na+/H+ exchange, possibly at the sarcolemma, could account for some of the changes to sarcoplasmic ionic levels observed. In a solution of low [Na] o, it is concluded that mitochondria could sequester at least 30% of the calcium accumulated by the cell even though the sarcoplasmic [Ca2+] does not exceed 0.3 microM. |
1(0,0,0,1) |