title: Further evidence for tonically functioning presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries.
abstract: Effects of dl- and d-carteolol alone on the release of tritium evoked by transmural field stimulation at 1 Hz were investigated in spirally cut guinea-pig pulmonary arteries preloaded with [3H]-norepinephrine. Cumulatively applied dl-carteolol 10(-8) M, 10(-7) M and 10(-6) M readily inhibited the release of tritium in a concentration-dependent manner, whereas the same concentrations of d-carteolol produced no effect. In conclusion, presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries tonically function to facilitate the release of the transmitter norepinephrine.
mesh_terms: D000818:Animals; D002354:Carteolol / Q000494:pharmacology*; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D011412:Propanolamines / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000032:analysis* / Q000294:innervation; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000502:physiology; D013237:Stereoisomerism; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D002354:Carteolol; D009638:Norepinephrine