Trifluoperazine and calmidazolium have multiple actions on the release of noradrenaline from sympathetic nerves of mouse atria. 1994

M Barrington, and H Majewski
Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.

The aim of this study was to determine whether the calmodulin inhibitors trifluoperazine (TFP) and calmidazolium (CMZ) could decrease the action-potential-evoked release of noradrenaline from mouse isolated atria incubated with [3H]-noradrenaline in support of the hypothesis that calmodulin is involved in neurotransmitter release. TFP (10 microM and 30 microM) significantly enhanced stimulation-induced (S-I) outflow of radioactivity from mouse atria but had no effect at 1.0 microM or 70 microM. TFP (70 microM) also significantly increased the spontaneous outflow of radioactivity. The facilitatory effect of TFP (10 microM) on S-I outflow of radioactivity persisted in either the presence of 3-isobutyl-1-methylxanthine (100 microM) or atropine (0.3 microM) indicating that this effect of TFP was not mediated through either inhibition of phosphodiesterases or through interference with presynaptic muscarinic receptors, respectively. In the presence of phentolamine, the facilitatory effect of TFP (10 microM) on S-I outflow was reduced but there was no effect on S-I outflow at 70 microM. However, in the presence of a combination of both phentolamine (1.0 microM) and the neuronal uptake blocker desipramine (1.0 microM) a significant inhibitory effect of TFP (70 microM) on the S-I outflow of radioactivity was observed, indicating that effects of TFP on presynaptic alpha-adrenoceptors and neuronal uptake had disguised an inhibitory effect on S-I noradrenaline release. Another inhibitor of the Ca(2+)-calmodulin complex, calmidazolium (CMZ, 10 microM) inhibited the S-I outflow of radioactivity but had no effect at 1.0 microM. However, CMZ (10 microM) also induced a concomitant increase in the spontaneous outflow of radioactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007093 Imidazoles Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
D008297 Male Males
D009206 Myocardium The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow. Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
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
D010646 Phentolamine A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and hypertensive emergencies, pheochromocytoma, vasospasm of RAYNAUD DISEASE and frostbite, clonidine withdrawal syndrome, impotence, and peripheral vascular disease. Fentolamin,Phentolamine Mesilate,Phentolamine Mesylate,Phentolamine Methanesulfonate,Phentolamine Mono-hydrochloride,Regitine,Regityn,Rogitine,Z-Max,Mesilate, Phentolamine,Mesylate, Phentolamine,Methanesulfonate, Phentolamine,Mono-hydrochloride, Phentolamine,Phentolamine Mono hydrochloride
D002147 Calmodulin A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels. Calcium-Dependent Activator Protein,Calcium-Dependent Regulator,Bovine Activator Protein,Cyclic AMP-Phosphodiesterase Activator,Phosphodiesterase Activating Factor,Phosphodiesterase Activator Protein,Phosphodiesterase Protein Activator,Regulator, Calcium-Dependent,AMP-Phosphodiesterase Activator, Cyclic,Activating Factor, Phosphodiesterase,Activator Protein, Bovine,Activator Protein, Calcium-Dependent,Activator Protein, Phosphodiesterase,Activator, Cyclic AMP-Phosphodiesterase,Activator, Phosphodiesterase Protein,Calcium Dependent Activator Protein,Calcium Dependent Regulator,Cyclic AMP Phosphodiesterase Activator,Factor, Phosphodiesterase Activating,Protein Activator, Phosphodiesterase,Protein, Bovine Activator,Protein, Calcium-Dependent Activator,Protein, Phosphodiesterase Activator,Regulator, Calcium Dependent
D003891 Desipramine A tricyclic dibenzazepine compound that potentiates neurotransmission. Desipramine selectively blocks reuptake of norepinephrine from the neural synapse, and also appears to impair serotonin transport. This compound also possesses minor anticholinergic activity, through its affinity to muscarinic receptors. Desmethylimipramine,Apo-Desipramine,Demethylimipramine,Desipramine Hydrochloride,Norpramin,Novo-Desipramine,Nu-Desipramine,PMS-Desipramine,Pertofran,Pertofrane,Pertrofran,Petylyl,Ratio-Desipramine,Apo Desipramine,Hydrochloride, Desipramine,Novo Desipramine,Nu Desipramine,PMS Desipramine,Ratio Desipramine
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
D004759 Enterochromaffin Cells A subtype of enteroendocrine cells found in the gastrointestinal MUCOSA, particularly in the glands of PYLORIC ANTRUM; DUODENUM; and ILEUM. These cells secrete mainly SEROTONIN and some neuropeptides. Their secretory granules stain readily with silver (argentaffin stain). Argentaffin Cells,5-HT-Containing Enterochromaffin Cells,Serotonin-Containing Enterochromaffin Cells,5 HT Containing Enterochromaffin Cells,5-HT-Containing Enterochromaffin Cell,Argentaffin Cell,Cell, Enterochromaffin,Cells, Enterochromaffin,Enterochromaffin Cell,Enterochromaffin Cell, 5-HT-Containing,Enterochromaffin Cell, Serotonin-Containing,Enterochromaffin Cells, 5-HT-Containing,Enterochromaffin Cells, Serotonin-Containing,Serotonin Containing Enterochromaffin Cells,Serotonin-Containing Enterochromaffin Cell
D006321 Heart The hollow, muscular organ that maintains the circulation of the blood. Hearts

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