The inhibitory action of prostaglandin f 2 alpha on release of tritium labeled noradrenaline enhanced by alpha 2 adrenoceptor blockade sodium pump inhibition and 4 amino pyridine in the main pulmonary artery of the rabbit
Torok, T.L.; Bunyevacz, Z.; Nguyen, T.T.; Hadhazy, P.; Magyar, K.; Vizi, E.S.
Neuropharmacology 23(1): 37-42
ISSN/ISBN: 0028-3908 Accession: 006702994
Large concentrations of prostaglandin F2.alpha. (PG F2.alpha.) inhibited the stimulation (2 Hz) evoked release of [3H]noradrenaline [NA, norepinephrine] from the isolated main pulmonary artery of the rabbit (the inhibition caused by 3 .times. 10-5 M PGF2.alpha. was 62%). PGF2.alpha. inhibited the release evoked by stimulation when it was enhanced by different procedures. During blockade of presynaptic .alpha.2-adrenoceptors by 3 .times. 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).