Spatially and functionally distinct Ca2+ stores in sarcoplasmic and endoplasmic reticulum.
The organization of calcium (Ca2+) stores in the sarcoplasmic and endoplasmic reticulum (S-ER) is poorly understood. The dynamics of the storage and release of calcium in the S-ER of intact, cultured astrocytes and arterial myocytes were studied with high-resolution imaging methods. The S-ER appeared to be a continuous tubular network; nevertheless, calcium stores in the S-ER were organized into small, spatially distinct compartments that functioned as discrete units. Cyclopiazonic acid (an inhibitor of the calcium pump in the S-ER membrane) and caffeine or ryanodine unloaded different, spatially separate compartments. Heterogeneity of calcium stores was also revealed in cells activated by physiological agonists. These results suggest that cells can generate spatially and temporally distinct calcium signals to control individual calcium-dependent processes.
Golovina
V A
VA
Department of Physiology and Center for Vascular Biology and Hypertension, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Blaustein
M P
MP
D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000648:ultrastructure; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D018871:Endoplasmic Reticulum, Smooth / Q000378:metabolism* / Q000648:ultrastructure; D005456:Fluorescent Dyes / Q000378:metabolism; D016257:Fura-2 / Q000031:analogs & derivatives / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D012433:Ryanodine / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D012701:Serotonin / Q000494:pharmacology
D005456:Fluorescent Dyes; D007211:Indoles; C058776:2-(2-(5-carboxy)oxazole)-5-hydroxy-6-aminobenzofuran-N,N,O-triacetic acid; D012433:Ryanodine; D012701:Serotonin; D002110:Caffeine; D018698:Glutamic Acid; D000252:Calcium-Transporting ATPases; D002118:Calcium; D016257:Fura-2; C000543:cyclopiazonic acid