The effects of 8-OH-DPAT on medullary 5-HT neurons and sympathetic activity in baroreceptor-denervated animals.
The effects of the 5HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on medullary 5-hydroxy-tryptamine (5-HT) neuronal firing and inferior cardiac sympathetic nerve activity were simultaneously determined in baroreceptor-denervated cats. 5-HT neuronal firing was inhibited by 50% at a 1 microgram/kg i.v. dose of 8-OH-DPAT in the baroreceptor-denervated animal. Unit firing was completely inhibited by a 3 microgram/kg dose. In contrast, 8-OH-DPAT inhibited inferior cardiac nerve activity between 10 and 100 micrograms/kg i.v. A similar relationship between the 8-OH-DPAT-induced inhibition of 5-HT unit activity and sympathetic nerve activity was observed in sham-operated control animals. These data suggest that the sympatholytic effects of 8-OH-DPAT cannot be explained on the basis of an autoreceptor effect of the drug.
King
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KA
Cardiovascular Disease Research, Upjohn Company, Kalamazoo, MI 49001.
McCall
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D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002415:Cats; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000294:innervation; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000187:drug effects*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*
D012702:Serotonin Antagonists; D013764:Tetrahydronaphthalenes; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin