Vasomotion has chloride-dependency in rat mesenteric small arteries

Area of Science:

• Physiology
• Vascular Biology
• Ion Channels

Background:

• Vascular tone oscillations (vasomotion) are critical for blood flow regulation.
• cGMP-independent and cGMP-dependent chloride conductances play roles in smooth muscle function.

Purpose of the Study:

• To investigate the role of calcium-activated chloride conductances (CaCCs) in vasomotion.
• To determine the contribution of specific chloride conductances to noradrenaline-stimulated arterial tone.

Main Methods:

• Isolated rat mesenteric small arteries were used for isometric tension measurements.
• Electrophysiological assessments were performed on isolated smooth muscle cells.
• Anion substitution and chloride channel blockers (DIDS, Zn2+) were employed.

Main Results:

• Chloride (Cl-) substitution with aspartate or thiocyanate (SCN-) inhibited vasomotion and associated oscillations.
• DIDS and Zn2+ blocked cGMP-dependent CaCCs but not cGMP-independent CaCCs.
• Vasomotion persisted with DIDS/Zn2+ but was sensitive to SCN-, indicating Cl- dependence.

Conclusions:

• Chloride ions are essential for the membrane potential and intracellular calcium oscillations underlying vasomotion.
• Both cGMP-dependent and cGMP-independent CaCCs appear to be important for regulating vascular tone.