Pre- and postsynaptic α-adrenergic receptor effects of trazodone in the anesthetized dog

✍ Scribed by Allen W. Gomoll; Keith Parmenter

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 384 KB
• Volume: 2
• Category: Article
• ISSN: 0272-4391
• DOI: 10.1002/ddr.430020606

✦ Synopsis

Abstract

The α‐adrenergic blocking properties of trazodone were assessed in spinal‐sectioned, vagotomized dogs. Both the inhibition by clonidine of the tachycardia produced by continuous cardiac accelerator nerve stimulation (presynaptic effect) and the vasopressor effects of clonidine (postsynaptic effect) were antagonized by trazodone and phentolamine in this model. The results indicate that although it is 12–18 times less potent on a weight basis, trazodone, like phentolamine, blocks presynaptic α‐adrenergic receptors on the cardiac nerves of anesthetized dogs. Trazodone, unlike imipramine, did not potentiate the positive inotropic responses elicited by exogenously administered norepinephrine. The latter observation supports the interpretation that trazodone altered positive chronotropic responses to cardiac accelerator nerve stimulation via presynaptic α‐receptor blockade rather than by either an interference with neuronal reuptake of norepinephrine or a heightening of ß‐adrenergic receptor sensitivity.