These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Electrophysiological evidence for an alpha 2-adrenergic inhibitory control of transmitter release in the rabbit mesenteric artery.
    Author: Illes P, Nörenberg W.
    Journal: Eur J Pharmacol; 1987 Nov 10; 143(2):151-61. PubMed ID: 2891548.
    Abstract:
    Excitatory junction potentials (e.j.p.s) evoked by nerve stimulation with 15 pulses at 1 Hz were recorded from muscle cells of the rabbit isolated mesenteric artery. Clonidine and B-HT 933 depressed all e.j.p.s in the train. The percentage inhibition was inversely related to the number of pulses. Yohimbine, rauwolscine and tolazoline reduced the early e.j.p. amplitudes but enhanced the later ones. The percentage facilitation of e.j.p.s increased with the number of pulses until a maximum was reached. Prazosin and corynanthine did not influence the first few e.j.p.s but potentiated the subsequent ones; their effects were less pronounced than those of yohimbine and rauwolscine. All the drugs antagonized the inhibition by clonidine but the effects of yohimbine and rauwolscine were more marked than those of prazosin and corynanthine. Phenylephrine, St 587 and noradrenaline depressed the e.j.p.s. Yohimbine diminished the effects of these substances and was a stronger antagonist of phenylephrine than prazosin. We suggest that, in the rabbit mesenteric artery, noradrenaline and the neuroeffector transmitter (probably ATP) are co-released from the terminals of postganglionic sympathetic nerves. Noradrenaline activates presynaptic alpha 2-adrenoceptors and thereby depresses transmitter release. The degree of presynaptic inhibition depends on the number of pulses applied, i.e. on the biophase concentration of noradrenaline.
    [Abstract] [Full Text] [Related] [New Search]