The fate of isoprenaline after inhibition of O-methylation and of extraneuronal uptake.
In order to study the fate of isoprenaline in the presence of drugs which inhibit its extraneuronal uptake and O-methylation, strips of canine lateral saphenous veins strips were incubated for 60 min with 3H-isoprenaline (2 microM) in the presence of cortexone 60 microM and U-0521 100 microM. Cortexone reduced to about 50% the amount of 3H-isoprenaline accumulated in the presence of U-0521 and the addition of cocaine further reduced it by about 30%. Field stimulation of strips treated with cortexone and U-0521 resulted in the release of significant, although small, amounts of 3H-isoprenaline; this release was prevented by cocaine or by pretreatment with reserpine. Thus, when extraneuronal uptake and O-methylation are inhibited, isoprenaline behaves like a false transmitter. Even in the presence of cortexone, U-0521 and cocaine, a considerable amount of isoprenaline accumulates in the strips, presumably in non-muscular structures of the tunica media.
D000818:Animals; D003042:Cocaine / Q000494:pharmacology; D003900:Desoxycorticosterone / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000378:metabolism*; D008745:Methylation; D009411:Nerve Endings / Q000378:metabolism*; D012110:Reserpine / Q000494:pharmacology; D012501:Saphenous Vein / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
D014316:Tritium; D003900:Desoxycorticosterone; D012110:Reserpine; D003042:Cocaine; D007545:Isoproterenol