%0 Journal Article %1 Zou_2002_6404 %A Zou, Hui %A Lifshitz, Lawrence M %A Tuft, Richard A %A Fogarty, Kevin E %A Singer, Joshua J %D 2002 %J Proc. Natl. Acad. Sci. U. S. A. %K 11983921 Aniline Animals, Bufo Caffeine, Calcium Calcium, Cations, Cell Channel Channels, Compounds, Conductivity, Cytosol, Dyes, Electric Electrophysiology, Factors, Fluorescence, Fluorescent Gating, Gov't, In Ion Membr, Microscopy, Muscle, Myocytes, P.H.S., Patch-Clamp Research Smooth Smooth, Spectrometry, Support, Techniques, Time U.S. Vitro, Xanthenes, ane, marinus, %N 9 %P 6404--6409 %R 10.1073/pnas.092654999 %T Visualization of Ca$^2+$ entry through single stretch-activated cation channels. %U http://dx.doi.org/10.1073/pnas.092654999 %V 99 %X Stretch-activated channels (SACs) have been found in smooth muscle and are thought to be involved in myogenic responses. Although SACs have been shown to be Ca$^2+$ permeable when Ca$^2+$ is the only charge carrier, it has not been clearly demonstrated that significant Ca$^2+$ passes through SACs in physiological solutions. By imaging at high temporal and spatial resolution the single-channel Ca$^2+$ fluorescence transient (SCCaFT) arising from Ca$^2+$ entry through a single SAC opening, we provide direct evidence that significant Ca$^2+$ can indeed pass through SACs and increase the local Ca$^2+$. Results were obtained under conditions where the only source of Ca$^2+$ was the physiological salt solution in the patch pipette containing 2 mM Ca$^2+$. Single smooth muscle cells were loaded with fluo-3 acetoxymethyl ester, and the fluorescence was recorded by using a wide-field digital imaging microscope while SAC currents were simultaneously recorded from cell-attached patches. Fluorescence increases at the cell-attached patch were clearly visualized before the simultaneous global Ca$^2+$ increase that occurred because of Ca$^2+$ influx through voltage-gated Ca$^2+$ channels when the membrane was depolarized by inward SAC current. From measurements of total fluorescence ("signal mass") we determined that about 18\% of the SAC current is carried by Ca$^2+$ at membrane potentials more negative than the resting level. This would translate into at least a 0.35-pA unitary Ca$^2+$ current at the resting potential. Such Ca$^2+$ currents passing through SACs are sufficient to activate large-conductance Ca$^2+$-activated K$^+$ channels and, as shown previously, to trigger Ca$^2+$ release from intracellular stores.

@article{Zou_2002_6404, abstract = {Stretch-activated channels (SACs) have been found in smooth muscle and are thought to be involved in myogenic responses. Although SACs have been shown to be {C}a$^{2+}$ permeable when {C}a$^{2+}$ is the only charge carrier, it has not been clearly demonstrated that significant {C}a$^{2+}$ passes through SACs in physiological solutions. By imaging at high temporal and spatial resolution the single-channel {C}a$^{2+}$ fluorescence transient (SCCaFT) arising from {C}a$^{2+}$ entry through a single SAC opening, we provide direct evidence that significant {C}a$^{2+}$ can indeed pass through SACs and increase the local [{C}a$^{2+}$]. Results were obtained under conditions where the only source of {C}a$^{2+}$ was the physiological salt solution in the patch pipette containing 2 mM {C}a$^{2+}$. Single smooth muscle cells were loaded with fluo-3 acetoxymethyl ester, and the fluorescence was recorded by using a wide-field digital imaging microscope while SAC currents were simultaneously recorded from cell-attached patches. Fluorescence increases at the cell-attached patch were clearly visualized before the simultaneous global {C}a$^{2+}$ increase that occurred because of {C}a$^{2+}$ influx through voltage-gated {C}a$^{2+}$ channels when the membrane was depolarized by inward SAC current. From measurements of total fluorescence ("signal mass") we determined that about 18\% of the SAC current is carried by {C}a$^{2+}$ at membrane potentials more negative than the resting level. This would translate into at least a 0.35-pA unitary {C}a$^{2+}$ current at the resting potential. Such {C}a$^{2+}$ currents passing through SACs are sufficient to activate large-conductance {C}a$^{2+}$-activated {K}$^{+}$ channels and, as shown previously, to trigger {C}a$^{2+}$ release from intracellular stores.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Zou, Hui and Lifshitz, Lawrence M and Tuft, Richard A and Fogarty, Kevin E and Singer, Joshua J}, biburl = {https://www.bibsonomy.org/bibtex/273b1d8524b8ed9e13966fd06b2c4fe3d/hake}, description = {The whole bibliography file I use.}, doi = {10.1073/pnas.092654999}, file = {Zou_2002_6404.pdf:Zou_2002_6404.pdf:PDF}, interhash = {8fae9b8ee7401de55b11e0917301341d}, intrahash = {73b1d8524b8ed9e13966fd06b2c4fe3d}, journal = {Proc. Natl. Acad. Sci. U. S. A.}, key = 262, keywords = {11983921 Aniline Animals, Bufo Caffeine, Calcium Calcium, Cations, Cell Channel Channels, Compounds, Conductivity, Cytosol, Dyes, Electric Electrophysiology, Factors, Fluorescence, Fluorescent Gating, Gov't, In Ion Membr, Microscopy, Muscle, Myocytes, P.H.S., Patch-Clamp Research Smooth Smooth, Spectrometry, Support, Techniques, Time U.S. Vitro, Xanthenes, ane, marinus,}, month = Apr, number = 9, pages = {6404--6409}, pii = {99/9/6404}, pmid = {11983921}, timestamp = {2009-06-03T11:21:39.000+0200}, title = {Visualization of {C}a$^{2+}$ entry through single stretch-activated cation channels.}, url = {http://dx.doi.org/10.1073/pnas.092654999}, volume = 99, year = 2002 }