Biomaterial Database

Contrasting effects of clonidine and 5-hydroxytryptophan on spinal sympathetic pathways. 1981

P W Madsen, and B D Hare, and C Sangdee, and D N Franz

The effects of clonidine HCI were compared with those of 5-HTP on transmission through two spinal sympathetic pathways, segmental spinal reflex pathways and descending intraspinal excitatory pathways, in unanesthetized spinal cats. Evoked sympathetic discharges were recorded from upper thoracic preganglionic rami. Clonidine (5-50 microgram/kg) produced a parallel, dose-dependent depression of transmission through each pathway. The intraspinal pathway was five time more sensitive than the spinal reflex pathway (ED50's, 6 and 30 microgram/kg), and the spinal reflex pathway could not be depressed by more than 60% even by higher doses. In contrast, 5-HTP was more effective in depressing the spinal reflex than the intraspinal pathway (ED50's 32 and 44 mg/kg), and both pathways could be depressed completely. Small doses of tolazoline or yohimbine rapidly antagonized the effects of clonidine but not 5-HTP. Clonidine and 5-HTP appear to depress the excitability of sympathetic preganglionic neurons by activating alpha2- and 5-HT receptors, respectively. Each mechanism may contribute independently to regulation of the sympathetic outflow.

UI	MeSH Term	Description	Entries
D009434	Neural Pathways	Neural tracts connecting one part of the nervous system with another.	Neural Interconnections,Interconnection, Neural,Interconnections, Neural,Neural Interconnection,Neural Pathway,Pathway, Neural,Pathways, Neural
D011941	Receptors, Adrenergic	Cell-surface proteins that bind epinephrine and/or norepinephrine with high affinity and trigger intracellular changes. The two major classes of adrenergic receptors, alpha and beta, were originally discriminated based on their cellular actions but now are distinguished by their relative affinity for characteristic synthetic ligands. Adrenergic receptors may also be classified according to the subtypes of G-proteins with which they bind; this scheme does not respect the alpha-beta distinction.	Adrenergic Receptors,Adrenoceptor,Adrenoceptors,Norepinephrine Receptor,Receptors, Epinephrine,Receptors, Norepinephrine,Adrenergic Receptor,Epinephrine Receptors,Norepinephrine Receptors,Receptor, Adrenergic,Receptor, Norepinephrine
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003000	Clonidine	An imidazoline sympatholytic agent that stimulates ALPHA-2 ADRENERGIC RECEPTORS and central IMIDAZOLINE RECEPTORS. It is commonly used in the management of HYPERTENSION.	Catapres,Catapresan,Catapressan,Chlophazolin,Clofelin,Clofenil,Clonidine Dihydrochloride,Clonidine Hydrochloride,Clonidine Monohydrobromide,Clonidine Monohydrochloride,Clopheline,Dixarit,Gemiton,Hemiton,Isoglaucon,Klofelin,Klofenil,M-5041T,ST-155,Dihydrochloride, Clonidine,Hydrochloride, Clonidine,M 5041T,M5041T,Monohydrobromide, Clonidine,Monohydrochloride, Clonidine,ST 155,ST155
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D006916	5-Hydroxytryptophan	The immediate precursor in the biosynthesis of SEROTONIN from tryptophan. It is used as an antiepileptic and antidepressant.	5-HTP,Hydroxytryptophan,Oxitriptan,Oxytryptophan,Tryptophan, 5-Hydroxy-,5 Hydroxytryptophan,5-Hydroxy- Tryptophan,Tryptophan, 5 Hydroxy
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013116	Spinal Cord	A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.	Coccygeal Cord,Conus Medullaris,Conus Terminalis,Lumbar Cord,Medulla Spinalis,Myelon,Sacral Cord,Thoracic Cord,Coccygeal Cords,Conus Medullari,Conus Terminali,Cord, Coccygeal,Cord, Lumbar,Cord, Sacral,Cord, Spinal,Cord, Thoracic,Cords, Coccygeal,Cords, Lumbar,Cords, Sacral,Cords, Spinal,Cords, Thoracic,Lumbar Cords,Medulla Spinali,Medullari, Conus,Medullaris, Conus,Myelons,Sacral Cords,Spinal Cords,Spinali, Medulla,Spinalis, Medulla,Terminali, Conus,Terminalis, Conus,Thoracic Cords
D013564	Sympathetic Nervous System	The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.	Nervous System, Sympathetic,Nervous Systems, Sympathetic,Sympathetic Nervous Systems,System, Sympathetic Nervous,Systems, Sympathetic Nervous