[Calcium hypothesis of Alzheimer disease].

Alzheimer's disease is the most common neurodegenerative disorder characterized by progressive memory and cognitive abilities loss. The etiology of Alzheimer's disease is poorly understood. In this regard, there is no effective treatment for the disease.

[Two types of store-operated channels in A431 cells].

Activation of phospholipase C-coupled receptors leads to the release of Ca2+ from Ca2+ stores, and subsequent activation of store-operated cation (SOC) channels, promoting sustained Ca2+ influx. The most studied SOC channels are CRAC ("calcium-release activated calcium") channels exhibiting a very high selectivity for Ca2+. However, there are many SOC channels permeable for Ca2+ but having a lower selectivity.

Low-conductivity calcium channels in the macrophage plasma membrane: activation by inositol-1,4,5-triphosphate.

Local voltage clamping was applied to mouse macrophage plasma membrane to study calcium channels activated by inositol-1,4,5-triphosphate (IP3) and blocked by heparin. These channels were clearly distinguished from IP3-activated channels of the endoplasmic reticulum by their low conductivity (about 1 pSm for 100 mM Ca2+), high selectivity for Ca2+ relative to K+ (P(Ca):P(K) > 1000), calcium inactivation, and activation on hyperpolarization; these properties allowed them to be assigned to the I(CRAC) family. On the other hand, the properties of the IP3 receptors of these channels (IP3R), i.

[Low conductivity calcium channels in the plasmatic membrane of macrophages: activation with inositol 1,4,5-triphosphate].

Using patch-clamp technique we have shown that the plasma membrane of mouse macrophages contains calcium channels that are activated by inositol (1, 4, 5)-trisphosphate (IP3) and blocked by heparine. Their conductivity properties strongly differentiate them from IP3-activated channels of endoplasmic reticulum, but make it possible to include them to the ICRAC family. By the other hand, properties of the IP3 receptor (IP3R) of our channels are similar to those of endoplasmic IP3R.