Table 1 Adrenergic, cholinergic, and angiotensin receptors and the effect of their activation in heart and lungs
From: Autonomic nervous system involvement in pulmonary arterial hypertension
Receptors | Receptor Sub-types | Activators | Heart | Lung |
|---|---|---|---|---|
Adrenergic | α | • Phenylephrine [79] • Epinephrine • Norepinephrine | • Increases rate of contraction (chronotropic) [80] • Selective α1-AR stimulation is negatively inotropic in RV trabeculae but positively inotropic in LV trabeculae [81] | • Increases pulmonary vascular resistance [7] • Decreases compliance |
|  | β1 | • Dobutamine [79] • Epinephrine • Norepinephrine | • Increases rate of contraction (chronotropic) [80] • Increases force of contraction (inotropic) • Increases excitability (predisposes to arrhythmia) • Increases AV nodal conduction velocity • LV and RV are equally inotropically responsive to selective β1-adrenergic receptor agonism [81] | • Decreases pulmonary vascular resistance [82] |
|  | β2 | • Procaterol [83] • Terbutaline • Salbutamol | • Increases cardiac contractility [83] • Increases inotropy • Does not predispose to arrhythmia • Increases fatty acid modulation and glucose metabolism. • Decreases myocardial apoptosis | • Dilation of bronchi and bronchioles [80] • Decreases pulmonary vascular resistance [82] |
Cholinergic | Muscarinic | • Acetylcholine [84] • Pilocarpine | • Decreases chronotropy [85] • Decreases inotropy • Decreases dromotropy • Expression of M(2,4) AChR in the right ventricle is higher than in the left ventricle [86] | • Decreases pulmonary vascular resistance via M3 receptor [84] |
|  | Nicotinic | • Acetylcholine | • Expression of α7-nAChR is higher in the left ventricle and right ventricle than the atria [86] | • Decreased pulmonary vascular resistance (α7-nAChR via NO pathway) • Promotes cell proliferation via MAPK pathway and neoangiogenesis via increased VEGF in pulmonary endothelium [87] |
Angiotensin | AT1 | • Angiotensin II | • Increases chronotropy [88] • Increases inotropy • Facilitates presynaptic release of noradrenaline from cardiac sympathetic nerve terminals • Causes coronary vessel vasoconstriction • Stimulates aldosterone release • Causes myocyte hypertrophy, non-myocyte proliferation, and interstitial fibrosis | • Increases pulmonary vascular resistance [62] • Promotes proliferation, inflammation, and fibrosis in the vasculature and lung parenchyma |
|  | AT2 | • Angiotensin II | • Counteracts effects of AT1 receptor in cardiac hypertrophy and remodeling – cardioprotective [88] • Involved in cell growth, proliferation, differentiation, migration, and apoptosis • Not clear if AT2 agonism has acute effects on vascular tone | • Decreases pulmonary vascular resistance [62] • Decreased inflammation • Diminished fibrosis • Promotes cell differentiation and apoptosis • Reduces cell proliferation |