Interactions of lithium with the adrenergic system in electrically-stimulated guinea pig myenteric plexus isolated preparations. Actions of a phosphodiesterase inhibitor.
The possible involvement of lithium in the mechanism of action of norepinephrine has been studied in electrically-stimulated preparations isolated from guinea pig myenteric plexus. Results show that concentrations of lithium above 0.5 x 10(-2) M significantly inhibit the norepinephrine effect. The results obtained when preparations were preincubated with alpha-adrenergic blocking agents (phenoxybenzamine and phentolamine) suggest a beta-adrenergic action of lithium since these substances induced 74% and 37% inhibition of the lithium effects, respectively. When preparations were preincubated with beta-adrenergic blocking agents (propranolol, toliprolol, atenolol and sotalol) the action of lithium was unchanged. A phosphodiesterase inhibitor also led to 50% inhibition of the lithium effects. These results, together with the fact that the adenylate cyclase cAMP system is linked directly to the beta-adrenoceptors, suggest that the inhibitory action of lithium on norepinephrine, in this preparation, is related to its beta-adrenergic action, which agrees with the results obtained in brain by other authors.
Marmol
F
F
Unit of Pharmacology, Therapeutics and Clinical Pharmacology, Faculty of Medicine, University of Barcelona, Spain.
Puig-Parellada
P
P
Forn
J
J
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology*; D008297:Male; D009197:Myenteric Plexus / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D010726:Phosphodiesterase Inhibitors; D008012:Lidocaine; D008094:Lithium; D000262:Adenylyl Cyclases; D015056:1-Methyl-3-isobutylxanthine; D009638:Norepinephrine