Rat arterial smooth muscle devoid of ryanodine receptor function: effects on cellular Ca2+ handling
Tóm tắt
The roles of intracellular Ca2+ stores and ryanodine (Ry) receptors for vascular Ca2+ homeostasis and viability were investigated in rat tail arterial segments kept in organ culture with Ry (10 – 100 μ Acute exposure to Ry or the non‐deactivating ryanodine analogue C10‐Oeq glycyl ryanodine (10 μ Ry receptor protein was detected on Western blots in arteries cultured either with or without Ry. Brief Ca2+ release events (sparks) were absent after culture with Ry, whereas Ca2+ waves still occurred. The propagation velocity of waves was equal (∼19 μm s−1) in tissue cultured either with or without Ry. Inhibition of Ca2+ accumulation into the sarcoplasmic reticulum (SR) by culture with caffeine (5 m Removal of Ca2+ from the cytosol following a Ca2+ load was retarded after Ry culture. Thapsigargin reduced the rate of Ca2+ removal in control cultured rings, but had no effect after Ry culture. It is concluded that intracellular Ca2+ stores recover during chronic Ry treatment, while Ry receptors remain non‐functional. Ry receptor activity is required for Ca2+ sparks and for SR‐dependent recovery from a Ca2+ load, but not for Ca2+ waves or basal Ca2+ homeostasis.
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Tài liệu tham khảo
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