Veterinary Neuropharmacology

PHARMACOLOGICAL ACTIONS

• Pharmacological actions of catecholamines can be studied under four major categories.
  • Excitatory
    • Blood vessels - constriction (including veins, increased venous return to heart).
    • Iris - contraction of the radial muscle with mydriasis .
    • GI & Urinary - contraction of the sphincters.
    • Sweat glands - secretion in horse.
    • Salivary glands - viscous secretion .
    • Male genetalia - ejaculation .
  • Inhibitory
    • Bronchioles - dilatation.
    • Blood vessels - dilatation.
    • GI Tract - relaxation of smooth muscle .
    • Urinary bladder - relaxation of detrusor .
  • Cardioexcitatory effects
    •  SA node - increased heart rate
    •  Atria & Ventricles - increased force of contraction, conduction velocity.
    • AV node & His Purkinje System - increased automaticity, conduction velocity.
  • Metabolic effects
    • Liver - glycogenolysis and gluconeogenesis, hyperglycemia.
    • Pancreas decrease (α) and increased (β) secretion.
    • Fat cells - lipolysis, increased plasma free fatty acids .
    • Skeletal - Muscle glycogenolysis, increased blood lactate .
• In addition to these effects, some CNS effects are also noticed.