TABLE 3:
Physiology and pharmacology of baroreceptor afferents
| Location Afferent nerves | Physiologic Stimulus | Pharmacologic Stimulants | Pharmacologic Inhibitors | Systemic Responses to Stimulations |
|---|---|---|---|---|
| Carotid sinus / Glossopharyngeal nerve (Cranial nerve IX) | ↑ AP | Adenosine (A1 receptor) (92) Arachidonic acid (345) Capsaicin (611) Endothelin-1 (low dose) (301) Nifedipine (Ca-dependent) (217) Prostacyclin – PGI2 (88, 345) Serotonin (5-HT3 receptors) (600) Simvastatin (362) Veratrum alkaloids (211) |
Agmatine (Ca-dependent, α2AR-mediated) (425)
Amiloride (stretch DEG/ENaC channels) (139) Benzamil (amiloride analog)(139) Bradykinin (PGs-independent, NO-mediated) (588) Doxapram (399) Endothelin-1 (ETAR, high dose) (301) 17beta-estradiol (574) Gadolinium (211) Ginkgolide B (diterpenoid trilactone) (572) Moxonidine (α2AR-mediated) (591) NSAIDs (aspirin, indomethacin) (345) Streptomycin (426) Verapamil (Na-dependent) (217) |
↓ Sympathetic activity ↑ Parasympathetic activity ∆ EEG asynchronization (179) ↓ “Sham rage” behavior (608) ↓ Somatomotor reflexes (e.g., analgesia) (56) ↓ Angina pectoris (57) |
|
Aortic arch / Vagal nerve (Cranial nerve X) |
↑ AP | Acetylcholine (mAchR/NO-mediated, low conc.) (372) Acetylcholine (direct, nAchR) (372) Prostacyclin – PGI2 (305) Norepinephrine (under distension) (1) |
Acetylcholine (mAChR/VSM-mediated, high conc.) (372) Amiloride (140) Angiotensin II (VSM contraction-mediated) (374) Norepinephrine (under contraction) (1) |
↓ Sympathetic activity ↑ Parasympathetic activity |
|
Cardiopulmonary structures / Vagal nerve (Cranial nerve X) |
Atrial and ventricular stretch ↑ Vascular volume ↑ Central venous pressure ↑ Lung inflation rate ↑ Lung stiffness Airways light touch |
Ammonia (230, 297) Bradykinin (37) Cigarette smoke, Nicotine (279, 534) Endotoxin (292) Histamine (37) Opiates (430) (systemic administration) Ozone (102) PBG/Serotonin (559) SP/capsaicin (37) Tumor necrosis factor-alpha (306) Veratrum alkaloids (339) |
↓ Sympathetic activity ↑ Parasympathetic activity ∆ EEG asynchronization (179) ↓ “Sham rage” behavior (608) ↓ Somatomotor reflexes, e.g., analgesia (56) |
|
|
Auricle (cymba conchae) / Vagal nerve (Cranial nerve X) |
Mechanical(216) (acupuncture) Electrical (TENS)(602) |
↓ Sympathetic activity (95) ↑ HRV (95) ↑ Mood (602) ↓ Major Depression (105) ↓ Seizure (216, 602) ↓ Chronic pain: migraine, pelvic pain, diabetic neuropathy (303, 370, 382) |
Note: Data obtained from the local administration of drugs in isolated afferents recording preparations except for opioids. AP: arterial blood pressure. α2AR: α2-adrenoceptors. EEG: electroencephalogram. ETAR: endothelin type-A receptor. HRV: heart rate variability. mAchR: muscarinic acetylcholine receptors. mAchR/NO: the mAchR-mediated release of NO in NE-pre-constricted artery. mAchR/VSM: mAchR-induced relaxation of vascular smooth muscle. nAchR: direct activation of nicotinic AchR (few baroreceptors). NE: norepinephrine. NO: nitric oxide. PBG: PGs: Prostaglandins. Phenylbiguanide, 5-HT3 receptor agonist. SP: Substance P. TENS: transcutaneous electrical nerve stimulation. VSM: vascular smooth muscle.