Abstract 10272: Microtubule Stability is Related to Mitochondrial Function in Rat Ventricular Myocytes
Backgrounds: The microtubules are major components of the cytoskeleton, and microtubule reorganization is supposed to be associated with the development of cardiac diseases. There is a close relationship between microtubules and mitochondrial function, such as mitochondrial permeability transition pore (mPTP). We investigated the relationship between microtubule organization and mitochondrial function in cardiac myocytes.
Methods: Isolated myocytes were obtained from male SD rats, and cells were permiabilized with saponin. We used paclitaxel to stabilize microtubules, and nocodazole to disrupt microtubules. The microtubule reorganization by each drug was evaluated with immunofluorescence staining with antibodies to α-tubulin. Then, we investigated the effects of each drug on mitochondrial membrane potential (ΔΨm ; measured with TMRE), and the opening of mPTP (assessed by calcein leakage from mitochondria) with a confocal microscopy.
Results: (1) The immunolabeling of α-tubulin showed that exposure to paclitaxel (10μM) or nocodazole (10μM) for 60 min stabilized or disrupted tubulin network, respectively. (2) Both paclitaxel (10μM) and nocodazole (10μM) depolarized ΔΨm (by 57.5±5.52% and 63.1±4.68% of the baseline, respectively, p<0.05). (3) Both paclitaxel and nocodazole induced calcein leakage from mitochondria (by 42.7±4.26% and 52.9±2.65% of the baseline, respectively, p<0.05). (4)The lower concentration of each drug (paclitaxel 1μM or nocodazole 1μM), did not alter α-tubulin network and there were no the significant change in both ΔΨm and mPTP under these conditions. (5) Cyclosporin A (an inhibitor of mPTP ; 0.4 μM) blocked both ΔΨm depolarization and calcein leakage, induced by paclitaxel or nocodazole.
Conclusion: Our results showed that both stabilization and disruption of microtubule opened mPTP and depolarized ΔΨm. It is indicated that microtubule disorganization plays an important role in the regulation of mitochondrial function in cardiac myocytes. These findings could be related to the mechanism for microtubule-medicated cardiac dysfunction.
- © 2011 by American Heart Association, Inc.