Abstract:
:The microenvironment between the plasma membrane and the near-membrane sarcoplasmic reticulum (SR) may play an important role in Ca(2+) regulation in smooth muscle cells. We used a three-dimensional mathematical model of Ca(2+) diffusion and regulation and experimental measurements of SR Ca(2+) uptake and the distribution of the SR in isolated smooth muscle cells to predict the extent that the near-membrane SR could load Ca(2+) after the opening of single plasma membrane Ca(2+) channels. We also modeled the effect of SR uptake on 1), single-channel Ca(2+) transients in the near-membrane space; 2), the association of Ca(2+) with Ca(2+) buffers in this space; and 3), the amount of Ca(2+) reaching the central cytoplasm of the cell. Our results indicate that, although single-channel Ca(2+) transients could increase SR Ca(2+) to a certain extent, SR Ca(2+) uptake is not rapid enough to greatly affect the magnitude of these transients or their spread to the central cytoplasm unless the Ca(2+) uptake rate of the peripheral SR is an order-of-magnitude higher than the mean rate derived from our experiments. Immunofluorescence imaging, however, did not reveal obvious differences in the density of SR Ca(2+) pumps or phospholamban between the peripheral and central SR in smooth muscle cells.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Bazzazi H,Kargacin ME,Kargacin GJdoi
10.1016/S0006-3495(03)74605-0subject
Has Abstractpub_date
2003-09-01 00:00:00pages
1754-65issue
3eissn
0006-3495issn
1542-0086pii
S0006-3495(03)74605-0journal_volume
85pub_type
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