A functional ryanodine-sensitive intracellular Ca2+ store is present in vascular endothelial cells

Area of Science:

• Cardiovascular Biology
• Cell Physiology
• Endothelial Cell Function

Background:

• The ryanodine receptor (RyR) presence in vascular endothelium is known, but its functional role remains unclear.
• Intracellular calcium (Ca2+) signaling is critical for endothelial cell function.
• Understanding Ca2+ regulation in endothelial cells is vital for cardiovascular health.

Purpose of the Study:

• To determine the presence of functional ryanodine-sensitive Ca2+ stores in various cultured vascular endothelial cells.
• To investigate the role of these stores in intracellular Ca2+ regulation and endothelial cell responses.

Main Methods:

• Primary cultured endothelial cells from rat aorta (RAECs), human aorta (HAECs), human umbilical vein (HUVECs), and bovine pulmonary artery (BPAECs) were used.
• Indo 1 fluorescence was employed to measure intracellular Ca2+ changes.
• Cells were exposed to ryanodine and various agonists (bradykinin, histamine) under different extracellular Ca2+ concentrations.

Main Results:

• HAECs, BPAECs, and HUVECs showed a slow intracellular Ca2+ increase with ryanodine at rest; RAECs did not.
• Ryanodine blunted the Ca2+ response to a second bradykinin exposure in RAECs.
• Higher extracellular Ca2+ concentrations enhanced ryanodine's effect on agonist-induced Ca2+ release in HUVECs.

Conclusions:

• Functional ryanodine-sensitive Ca2+ stores are present in vascular endothelial cells.
• These stores are involved in regulating Ca2+ storage and release from agonist-sensitive intracellular compartments.
• Ryanodine receptor activity in endothelial cells influences intracellular Ca2+ dynamics.