Harmane produces hypotension following microinjection into the RVLM: possible role of I(1)-imidazoline receptors.
The beta-carboline, harmane (0.1 - 1.0 nmol) produces dose dependent hypotension when microinjected unilaterally into the rostral ventrolateral medulla (RVLM) of the anaesthetized rat. The potency of harmane on blood pressure is similar to that of the imidazoline, clonidine. The hypotensive effects of both clonidine and harmane are reversed by microinjection of the relatively I(1)-receptor selective antagonist efaroxan (20 nmol). These results are consistent with harmane acting at an I(1)-receptor in the RVLM. This is the first report of an endogenous ligand for I(1)-receptors that has central effects on blood pressure.
Musgrave
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Department of Medical Laboratory Science, RMIT, Melbourne 3001 Australia. Department of Medicine, Monash University, Clayton, 3168 Australia. ian.musgrave@rmit.edu.au
Badoer
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D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001572:Benzofurans / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006247:Harmine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced*; D007093:Imidazoles / Q000494:pharmacology; D054755:Imidazoline Receptors; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000037:antagonists & inhibitors / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D001572:Benzofurans; D007093:Imidazoles; D054755:Imidazoline Receptors; D011955:Receptors, Drug; D006247:Harmine; C005010:harman; C062597:efaroxan; D003000:Clonidine