Biomaterial Database

Peripheral vascular actions of alpha-methyldopa in the dog. 1977

E Rodrigues-Pereira

The aim of these study was to investigate peripheral vascular actions of alpha-methyldopa. The following experimental procedures were used: hind-limb of the dog perfused with the animals own blood or with Krebs solution; nictitating membrane of the dog; isolated and perfused segments of the saphenous vein of the dog; superfused strips of the saphenous vein of the dog. In these preparations, effects of alpha-methyldopa on responses elicited by electrical stimulation and on release of 3H-noradrenaline were studied. In dogs pretreated with alpha-methyldopa (200 mg/kg, i.v., 36, 24 and 4 hr before the experiment) contractions of the nictitating membrane caused by cervical sympathetic electrical stimulation were markedly reduced: however, the frequency--response curve to stimulation in the hind-limb and responsiveness to noradrenaline were not significantly different of controls. Perfusion of the hind-limb with Krebs containing alpha-methyldopa (2.2 mM) resulted in a significant reduction of perfusion pressure responses to lumbar sympathetic electrical stimulation with augmented responsiveness to exogenous noradrenaline. Similar results were obtained in in vitro experiments. Effects of alpha-methyldopa were not prevented by cocaine nor by inhibition of decarboxylase by Ro 4-4602 (D,L-serine,2-(2,3,4-,trihydroxybenzyl) hydrazine hydrochloride). Alpha-methyldopa depresses the release of tritiated compounds evoked by electrical stimulation, in saphenous vein strips. This suggests that inhibition of transmitter release could be an important factor to understand peripheral actions of alpha-methyldopa.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008750	Methyldopa	An alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. Its primary clinical use is as an antihypertensive agent.	Methyldopate,alpha-Methyldopa,Aldomet,Alphamethyldopa,Apo-Methyldopa,Dopamet,Dopegit,Dopegyt,Dopergit,Hydopa,Meldopa,Nu-Medopa,Sembrina,alpha-Methyl-L-Dopa,Apo Methyldopa,Nu Medopa,alpha Methyl L Dopa,alpha Methyldopa
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D009435	Synaptic Transmission	The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.	Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D009541	Nictitating Membrane	A fold of the mucous membrane of the CONJUNCTIVA in many animals. At rest, it is hidden in the medial canthus. It can extend to cover part or all of the cornea to help clean the CORNEA.	Third Eyelid,Eyelid, Third,Eyelids, Third,Membrane, Nictitating,Membranes, Nictitating,Nictitating Membranes,Third Eyelids
D009638	Norepinephrine	Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic.	Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D012039	Regional Blood Flow	The flow of BLOOD through or around an organ or region of the body.	Blood Flow, Regional,Blood Flows, Regional,Flow, Regional Blood,Flows, Regional Blood,Regional Blood Flows
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
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