Biomaterial Database

Actions of methoxamine and tryptamine and their interactions with cyproheptadine and phenoxybenzamine on cat spinal cord segmental reflexes. 1976

D B Vaupel, and W R Martin

The effects of norepinephrine, methoxamine and tryptamine were assessed on the monosynaptic and polysynaptic segmental reflexes in the unanesthetized, decerebrated acute spinal cat. Their selectivity of action was determined by studying the interactions of methoxamine and tryptamine with two antagonists, cyproheptadine and phenoxybenzamine. Potentials were evoked by stimulating either the L7 or S1 dorsal root and were recorded from the corresponding ipsilateral ventral root. Norepinephrine did not affect reflex activity, whereas methoxamine facilitated both the monosynaptic and polysynaptic potentials in a dose-related manner when infused over 20 minutes. Tryptamine facilitated both the monosynaptic and polysynaptic reflex potentials. This increase was dose related for the monosynaptic reflex but not for the polysynaptic reflex. Phenoxybenzamine blocked the facilitatory effects of methoxamine and did not antagonize the effects of tryptamine on the segmental reflex. The facilitatory effects of tryptamine were effectively blocked by cyproheptadine. Cyproheptadine failed to reduce the polysynaptic response to methoxamine, although it partially antagonized the monosynaptic facilitation. These findings demonstrate that methoxamine and tryptamine facilitate the segmental reflex by different modes of action and provide additional evidence for noradrenergic and tryptaminergic systems in the spinal cord.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008729	Methoxamine	An alpha-1 adrenergic agonist that causes prolonged peripheral VASOCONSTRICTION.	Methoxamedrin,Methoxamine Hydrochloride,Metoxamine Wellcome,Vasoxin,Vasoxine,Vasoxyl,Vasylox,Hydrochloride, Methoxamine,Wellcome, Metoxamine
D010643	Phenoxybenzamine	An alpha-adrenergic antagonist with long duration of action. It has been used to treat hypertension and as a peripheral vasodilator.	Dibenylene,Dibenyline,Dibenziran,Dibenzylin,Dibenzyline,Dibenzyran,Phenoxybenzamine Hydrochloride,Hydrochloride, Phenoxybenzamine
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D012023	Reflex, Monosynaptic	A reflex in which the AFFERENT NEURONS synapse directly on the EFFERENT NEURONS, without any INTERCALATED NEURONS. (Lockard, Desk Reference for Neuroscience, 2nd ed.)	Monosynaptic Reflex
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
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
D003533	Cyproheptadine	A serotonin antagonist and a histamine H1 blocker used as antipruritic, appetite stimulant, antiallergic, and for the post-gastrectomy dumping syndrome, etc.	Antergan,Dihexazin,Periactin,Peritol,Viternum
D004347	Drug Interactions	The action of a drug that may affect the activity, metabolism, or toxicity of another drug.	Drug Interaction,Interaction, Drug,Interactions, Drug
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical