Caveolar systems and sarcoplasmic reticulum in coronary smooth muscle cells of the mouse

Pharmacological Modulation of Sarcoplasmic Reticulum Function in Smooth Muscle

“…It has been known for some time that mitochondria frequently envelop the central and peripheral portions of the SR (Forbes et al, 1979). Furthermore, mitochondria isolated from smooth muscle cells actively sequester Ca 2ϩ , as demonstrated by Somlyo and Somlyo (1971).…”

“…Furthermore, mitochondria isolated from smooth muscle cells actively sequester Ca 2ϩ , as demonstrated by Somlyo and Somlyo (1971). The mitochondria are also, in many instances, located near the caveolae (Somlyo, 1975;Forbes et al, 1979), and this raises the possibility of transfer of ions between these three structures. Some direct evidence for an important regulatory role of mitochondria on intracellular Ca 2ϩ homeostasis were provided by Loew et al (1994), Tuft (1999), andMuir (1999).…”

“…In general, the peripheral SR is located close to the plasma membrane and sometimes in apposition with the caveolae (equivalent to junctional SR described above). This SR element is in contact with the deep SR positioned near the myofilaments and is in continuity with the central SR deeper within the cell and associated with the nuclear membrane (Forbes et al, 1977(Forbes et al, , 1979. Notable details of the analogy of smooth muscle SR to that of striated muscle have been painstakingly pointed out by Forbes et al (1979) who described as "peripheral SR" the collection of saccules, tubules, and cisternae lying in close apposition (gap of 10 -20 nm) to the inner plasmalemmal surface.…”

“…This SR element is in contact with the deep SR positioned near the myofilaments and is in continuity with the central SR deeper within the cell and associated with the nuclear membrane (Forbes et al, 1977(Forbes et al, , 1979. Notable details of the analogy of smooth muscle SR to that of striated muscle have been painstakingly pointed out by Forbes et al (1979) who described as "peripheral SR" the collection of saccules, tubules, and cisternae lying in close apposition (gap of 10 -20 nm) to the inner plasmalemmal surface. One functional implication of the peripheral SR is that it dampens the impact of the basal Ca 2ϩ entry by acting as a "superficial buffer barrier" (SBB), which then reinforces this buffering capacity by causing a vectorial extrusion of Ca 2ϩ to the extracellular space (van Breemen et al, 1995) (Fig.…”

Caveolae and Endoplasmic Reticulum: Immunofluorescence Microscopy and Time-Lapse Analysis.

“…In smooth muscle cells, caveolae and the SR have been shown to be closely apposed, and the relationship is thought to provide a mechanism for the coupling of Na+/ Ca2+ exchange at the plasma membrane and Ca2+ release from the SR [5]. We hypothesized that caveolae are engaged in intracellular Ca2+ regulation [6,8,9].…”