Biomaterial Database

Effects of harmala alkaloids on transmembrane potentials of guinea-pig papillary muscles. 1982

R G Carpentier

1 The significance of the presence of a methoxy group in the 7 position of the indole nucleus of harmala alkaloids in terms of their effects on the action potential of cardiac muscle was analysed. Guinea-pig papillary muscles were superfused with Tyrode solution at 30 degrees C and exposed to harmine or its analogue harmane, in which the methoxy group has been removed from the molecule. 2 Harmine 2 x 10(-5) M enhanced the amplitude of the action potential (AAP) of normal fibres and of slow responses elicited by noradrenaline in fibres depolarized by 21.6 mM K+-Tyrode. The effect of harmine on AAP occurred in the absence of any change in membrane resting potential or maximum velocity of the upstroke and it was abolished by propranolol. Harmane 2 x 10(-5) M did not have any effect on normal action potentials and slow responses. 3 Higher concentrations of the two analogues depressed both AAP and the maximum velocity of the upstroke of the action potential, without affecting the duration of the action potential. 4 It is concluded that: (a) removal of the methoxy group from harmine (1) abolishes the catechol-mediated stimulatory effect of a low concentration of the drug on the slow component of the upstroke of the action potential, and (2) does not modify the depressant effect of a high concentration of the drug. (b) The two analogues, harmine and harmane, do not affect the duration of the action potential of ventricular muscle.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D010210	Papillary Muscles	Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.	Muscle, Papillary,Muscles, Papillary,Papillary Muscle
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
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006247	Harmine	Alkaloid isolated from seeds of PEGANUM HARMALA; ZYGOPHYLLACEAE. It is identical to banisterine, or telepathine, from Banisteria caapi and is one of the active ingredients of hallucinogenic drinks made in the western Amazon region from related plants. It has no therapeutic use, but (as banisterine) was hailed as a cure for postencephalitic PARKINSON DISEASE in the 1920's.	9H-Pyrido(3,4-b)indole, 7-methoxy-1-methyl-,Banisterine,Leucoharmine,Telepathine,Yageine
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000470	Alkaloids	Organic nitrogenous bases. Many alkaloids of medical importance occur in the animal and vegetable kingdoms, and some have been synthesized. (Grant & Hackh's Chemical Dictionary, 5th ed)	Alkaloid,Plant Alkaloid,Plant Alkaloids,Alkaloid, Plant,Alkaloids, Plant
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
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships