Ca(2+) spark sites in smooth muscle cells are numerous and differ in number of ryanodine receptors, large-conductance K(+) channels, and coupling ratio between them.
Zhuge R, Fogarty KE, Baker SP, McCarron JG, Tuft RA, Lifshitz LM, Walsh JV. Ca(2+) spark sites in smooth muscle cells are numerous and differ in number of ryanodine receptors, large-conductance K(+) channels, and coupling ratio between them. Am J Physiol Cell Physiol. 2004 Dec; 287(6):C1577-88.