title: The inhibitory action of PGF2 alpha on release of [3H]noradrenaline enhanced by alpha 2-adrenoceptor blockade, sodium-pump inhibition and 4-aminopyridine in the main pulmonary artery of the rabbit.
abstract: Large concentrations of prostaglandin PGF2 alpha inhibited the stimulation (2 Hz) evoked release of [3H]noradrenaline from the isolated main pulmonary artery of the rabbit (the inhibition caused by 3 X 10(-5) M PGF2 alpha was 62%). Furthermore, PGF2 alpha inhibited the release evoked by stimulation when it was enhanced by different procedures. During blockade of presynaptic alpha 2-adrenoceptors by 3 X 10(-7) M yohimbine, which by itself enhanced the overflow of [3H]NA in response to stimulation, the inhibitory action of PGF2 alpha was more pronounced (78.2%). In tissue in which the Na+-pump was inhibited (K+-free treatment) where the overflow of 3H was markedly increased, PGF2 alpha exerted nearly equal inhibition of transmitter release to that observed in control experiments (64.3%). The inhibitory effect of PGF2 alpha on the stimulation-evoked release of [3H]NA was less pronounced (32.1%) in the presence of 10(-4) M 4-aminopyridine (a blocker of K+-channels).
mesh_terms: D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D015237:Dinoprost; D004558:Electric Stimulation; D005260:Female; D007473:Ion Channels / Q000187:drug effects; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011460:Prostaglandins F / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000378:metabolism*; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism; D015016:Yohimbine / Q000494:pharmacology*
chemical_list: D000631:Aminopyridines; D007473:Ion Channels; D011460:Prostaglandins F; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D012964:Sodium; D015237:Dinoprost; D015761:4-Aminopyridine; D011188:Potassium; D009638:Norepinephrine