The Adrenergic System in Vascular Smooth Muscle

Classics in Chemical Neuroscience: Xylazine

“…In the peripheral nervous system, agonism of α 2 receptors present on blood vessels leads to vasoconstriction, inhibition of pancreatic insulin secretion, platelet aggregation, inhibition of saliva production by salivary glands, and decreased gastrointestinal motility . Xylazine can elicit paradoxical blood pressure changes, with an initial blood pressure increase from α 2 agonism on vascular smooth muscle leading to vasoconstriction, followed by a longer lasting blood pressure decrease from α 2 agonism in the central nervous system and endothelium-dependent vasodilation . In humans, the clinical presentations of α 2 agonism by xylazine manifests as hypotension (sometimes preceded by hypertension), lethargy, drowsiness, hyperglycemia, bradycardia, and potential apnea requiring intubation. − A summary of the available pharmacological parameters of xylazine in humans is provided in Table .…”

“…58 Recently, general α 2 receptor distribution in the living human brain has been further elucidated with 11 C-yohimbine PET, illustrating a broad distribution 59 with variations in binding between participants and sexes. 59 In the peripheral nervous system, agonism of α 2 receptors present on blood vessels leads to vasoconstriction, 60 inhibition of pancreatic insulin secretion, 61 platelet aggregation, 62 inhibition of saliva production by salivary glands, and decreased gastrointestinal motility. 63 Xylazine can elicit paradoxical blood pressure changes, with an initial blood pressure increase from α 2 agonism on vascular smooth muscle leading to vasoconstriction, followed by a longer lasting blood pressure decrease from α 2 agonism in the central nervous system and endotheliumdependent vasodilation.…”