Smooth muscle cells affect endothelial membrane potential in rat aorta

Area of Science:

• Vascular biology
• Endothelial function
• Electrophysiology

Background:

• The endothelium plays a crucial role in regulating vascular tone.
• Understanding the electrophysiological effects of vasoconstrictors on the endothelium is vital for cardiovascular research.

Purpose of the Study:

• To investigate the impact of various vasoconstrictors on the membrane potential of rat aortic endothelium.
• To elucidate the signaling pathways involved in vasoconstrictor-induced endothelial responses.

Main Methods:

• Patch-clamp technique applied to intact rat aorta endothelium.
• Application of diverse vasoconstrictors (e.g., norepinephrine, endothelin-1, 5-HT) and receptor agonists/antagonists.
• Investigation of voltage-operated calcium channels and nitric oxide synthase pathways.

Main Results:

• Norepinephrine, endothelin-1, 5-HT, vasopressin, and angiotensin II induced depolarization and oscillations in endothelial membrane potential.
• Alpha-1 adrenergic agonists triggered oscillations, while other receptor agonists did not.
• Calcium channel blockers inhibited oscillations, while a calcium channel agonist enhanced them.
• Nitric oxide synthase inhibitors and methylene blue enhanced oscillations.
• Endothelial removal abolished responses to phenylephrine and endothelin-1, indicating a smooth muscle-to-endothelium signaling mechanism.

Conclusions:

• Vasoconstrictors acting on aortic smooth muscle receptors can induce electrical responses in the endothelium.
• These responses involve calcium influx and are modulated by nitric oxide signaling.
• The findings highlight a novel mechanism of intercellular communication in the aortic wall.