Implantable stimulating electrode for baroreceptor afferent nerves in rabbits

Area of Science:

• Biomedical Engineering
• Neuroscience
• Cardiovascular Research

Background:

• Baroreceptor afferent nerves are crucial for regulating blood pressure.
• Existing electrode technologies face limitations in long-term implantation and flexibility.
• Freely moving animal models are essential for studying neural regulation of cardiovascular function.

Purpose of the Study:

• To develop and evaluate a novel implantable stimulating electrode for baroreceptor afferent nerves.
• To assess the long-term efficacy and reliability of the electrode in a freely moving rabbit model.
• To investigate the effects of stimulating depressor and carotid sinus nerves on heart rate and blood pressure.

Main Methods:

• Development of a flexible electrode using platinum-iridium wire and silicone rubber insulation.
• Implantation of the electrode onto baroreceptor afferent nerves (0.1-0.2 mm diameter) in freely moving rabbits.
• In vitro and in vivo testing to assess electrode performance, durability, and current leakage.
• Recording of heart rate and blood pressure responses to nerve stimulation.

Main Results:

• The developed electrode demonstrated effectiveness for up to 245 days post-implantation.
• Early electrode failures were attributed to dislodgement, while later failures involved cable breakage.
• In vitro studies indicated some current leakage, but in vivo measurements validated the method's effectiveness.
• Stimulation of depressor and carotid sinus nerves, individually and combined, elicited measurable cardiovascular responses.

Conclusions:

• The novel flexible electrode is a viable tool for long-term baroreceptor nerve stimulation in freely moving animals.
• Durability challenges, such as dislodgement and cable breakage, require further engineering improvements.
• The study validates the in vivo application of this electrode for investigating neural control of blood pressure.