Release of Ca2+ from the sarcoplasmic reticulum increases mitochondrial [Ca2+] in rat pulmonary artery smooth muscle cells
Department of Physiology
Adenosine Triphosphate; Animals; Caffeine; Calcium; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Cytosol; Fluorescent Dyes; Ionophores; Male; Membrane Potentials; Mitochondria, Muscle; Patch-Clamp Techniques; Phosphodiesterase Inhibitors; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Receptors, Purinergic; Ryanodine; Sarcoplasmic Reticulum
Life Sciences | Medicine and Health Sciences
1. The Ca2+-sensitive fluorescent indicator rhod-2 was used to measure mitochondrial [Ca2+] ([Ca2+]m) in single smooth muscle cells from the rat pulmonary artery, while simultaneously monitoring cytosolic [Ca2+] ([Ca2+]i) with fura-2. 2. Application of caffeine produced an increase in [Ca2+]i and also increased [Ca2+]m. The increase in [Ca2+]m occurred after the increase in [Ca2+]i, and remained elevated for a considerable time after [Ca2+]i had returned to resting values. 3. The protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), which causes the mitochondrial membrane potential to collapse, markedly attenuated the increase in [Ca2+]m following caffeine application and also increased the half-time for recovery of [Ca2+]i to resting values. 4. Activation of purinoceptors with ATP also produced increases in both [Ca2+]i and [Ca2+]m in these smooth muscle cells. In some cells, oscillations in [Ca2+]i were observed during ATP application, which produced corresponding oscillations in [Ca2+]m and membrane currents. 5. This study provides direct evidence that Ca2+ release from the sarcoplasmic reticulum, either through ryanodine or inositol 1,4, 5-trisphosphate (InsP3) receptors, increases both cytosolic and mitochondrial [Ca2+] in smooth muscle cells. These results have potential implications both for the role of mitochondria in Ca2+ regulation in smooth muscle, and for understanding how cellular metabolism is regulated.
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Citation: J Physiol. 1999 Apr 1;516 ( Pt 1):139-47.
The Journal of physiology
Drummond, Robert M. and Tuft, Richard A., "Release of Ca2+ from the sarcoplasmic reticulum increases mitochondrial [Ca2+] in rat pulmonary artery smooth muscle cells" (1999). Open Access Articles. 1494.