From the Guidelines
The neural regulation of coronary circulation is primarily controlled by the autonomic nervous system, including the sympathetic and parasympathetic nervous systems, which work together to regulate blood flow to the heart muscle based on myocardial oxygen demand. The sympathetic nervous system increases coronary blood flow through beta-adrenergic receptors, causing vasodilation of coronary vessels when activated by norepinephrine and epinephrine 1. This vasodilation is crucial during exercise or stress when the heart requires more oxygen. The parasympathetic system, acting through the vagus nerve and acetylcholine release, generally promotes vasodilation via nitric oxide production from endothelial cells.
The regulation of coronary circulation also involves local metabolic factors, such as adenosine, potassium ions, and hydrogen ions produced during cardiac work, which contribute significantly to autoregulation, ensuring blood flow matches the heart's metabolic needs 1. The intrinsic cardiac nervous system, which includes afferent, efferent, and local circuit neurons, plays a crucial role in regulating heart dynamics and coronary blood flow 1. The central nervous system interacts dynamically with the autonomic nervous system to promote control of the heart, as hypothesized by the neurovisceral integration model 1.
Key factors that influence coronary circulation include:
- Myocardial oxygen demand
- Autoregulation of coronary blood flow
- Sympathetic and parasympathetic nervous system activity
- Local metabolic factors
- Intrinsic cardiac nervous system activity
- Central nervous system interaction with the autonomic nervous system. The balance between these factors is essential for maintaining cardiac function and preventing myocardial ischemia and potential tissue damage.
From the Research
Neural Regulation of Coronary Circulation
The neural regulation of coronary circulation is a complex process involving the autonomic nervous system, which plays a crucial role in maintaining cardiovascular homeostasis. The key concepts related to this process are:
- The sympathetic and parasympathetic nervous systems have a dominant role in cardiovascular control, with effects on cardiac rate, contractility, and vascular resistance 2.
- The autonomic nervous system regulates coronary circulation through multiple levels of control, including motor circuits, sensory neurons, and the intrinsic cardiac nervous system 3.
- The role of the autonomic nervous system in hypertension has been studied using bond graph models, which demonstrate the importance of sympathetic and parasympathetic activities in modifying systemic peripheral vascular resistance, heart rate, and ventricular end-systolic elastance 4.
Mechanisms of Neural Regulation
The mechanisms of neural regulation of coronary circulation involve:
- Feedforward regulation, often referred to as "central command," which contributes to overall cardiovascular homeostasis 5.
- Feedback or reflex regulation, which includes the baroreceptor, chemoreceptor, and other reflexes that work together to regulate blood pressure and blood oxygenation 5.
- The brain mechanisms that defend the body against environmental challenges, such as dehydration, cold, and heat stress 5.
- The central mechanisms regulating cardiovascular function associated with different behaviors, including defensive behavior and exercise 5.
Key Findings
Key findings related to the neural regulation of coronary circulation include:
- The importance of sympathetic and parasympathetic activities in regulating coronary circulation 2, 3, 4.
- The role of the autonomic nervous system in maintaining cardiovascular homeostasis during various physiological perturbations, including changes in posture, physical activity, and temperature 6.
- The use of microneurography to study the reflex regulation of skeletal muscle sympathetic nerve activity by arterial baroreceptors, arterial chemoreceptors, and cardiopulmonary baroreceptors 6.