A quantitative model for refilling of the sarcoplasmic reticulum during vascular smooth muscle asynchronous [Ca2+] oscillations
نویسندگان
چکیده
We have developed a quantitative model for the creation of cytoplasmic Ca gradients near the inner surface of the plasma membrane (PM). In particular we simulated the refilling of the sarcoplasmic reticulum (SR) via PM-SR junctions during asynchronous [Ca2+]i oscillations in smooth muscle cells of the rabbit inferior vena cava. We have combined confocal microscopy data on the [Ca2+]i oscillations, force transduction data from cell contraction studies and electron microscopic images to build a basis for computational simulations that model the transport of calcium ions from Na/Ca exchangers (NCX) on the PM to sarcoplasmic/endoplasmic reticulum Ca ATPase (SERCA) pumps on the SR as a three-dimensional random walk through the PM-SR junctional cytoplasmic spaces. Electron microscopic ultrastructural images of the smooth muscle cells were elaborated with software algorithms to produce a very clear and dimensionally accurate picture of the PM-SR junctions. From this study, we conclude that it is plausible and possible for enough Ca to pass through the PM-SR junctions to replete the SR during the regenerative Ca release, which underlies agonist induced asynchronous Ca oscillations in vascular smooth muscle.
منابع مشابه
A quantitative model for refilling of the sarcoplasmic reticulum during vascular smooth muscle asynchronous [Ca] oscillations
We have developed a quantitative model describing the refilling of the sarcoplasmic reticulum during asynchronous [Ca2+]i oscillations in smooth muscle cells of the rabbit inferior vena cava. We have combined confocal microscopy data on the [Ca2+]i oscillations, force transduction data from cell contraction studies and electron microscopy images to build a basis for computational simulations th...
متن کاملMitochondrial regulation of sarcoplasmic reticulum Ca2+ content in vascular smooth muscle cells.
Subplasmalemmal ion fluxes have global effects on Ca(2+) signaling in vascular smooth muscle. Measuring cytoplasmic and mitochondrial [Ca(2+)]and [Na(+)], we previously showed that mitochondria buffer both subplasmalemmal cytosolic [Ca(2+)] and [Na(+)] in vascular smooth muscle cells. We have now directly measured sarcoplasmic reticulum [Ca(2+)] in aortic smooth muscle cells, revealing that mit...
متن کاملMitochondrial Regulation of Sarcoplasmic Reticulum Ca Content in Vascular Smooth Muscle Cells
Subplasmalemmal ion fluxes have global effects on Ca signaling in vascular smooth muscle. Measuring cytoplasmic and mitochondrial [Ca ]and [Na ], we previously showed that mitochondria buffer both subplasmalemmal cytosolic [Ca ] and [Na ] in vascular smooth muscle cells. We have now directly measured sarcoplasmic reticulum [Ca ] in aortic smooth muscle cells revealing that mitochondrial Na /Ca ...
متن کاملMechanism of nitric oxide-induced vasodilatation: refilling of intracellular stores by sarcoplasmic reticulum Ca2+ ATPase and inhibition of store-operated Ca2+ influx.
The precise mechanisms by which nitric oxide (NO) decreases free [Ca2+]i, inhibits Ca2+ influx, and relaxes vascular smooth muscle are poorly understood. In rabbit and mouse aorta, agonist-induced contractions and increases in [Ca2+]i were resistant to nifedipine, suggesting Ca2+ entry through non-L-type Ca2+ channels. Relaxations to NO were inhibited by thapsigargin (TG) or cyclopiazonic acid ...
متن کاملWaves of Calcium Depletion in the Sarcoplasmic Reticulum of Vascular Smooth Muscle Cells: An Inside View of Spatiotemporal Ca2+ Regulation
Agonist-stimulated smooth muscle Ca2+ waves regulate blood vessel tone and vasomotion. Previous studies employing cytoplasmic Ca2+ indicators revealed that these Ca2+ waves were stimulated by a combination of inositol 1,4,5-trisphosphate- and Ca2+ -induced Ca2+ release from the endo/sarcoplasmic reticulum. Herein, we present the first report of endothelin-1 stimulated waves of Ca2+ depletion fr...
متن کامل