title: MK-801 enhances noradrenergic neurotransmission in rat vas deferens.
abstract: The effect of MK-801 (dizocilpine) on the noradrenergic neurotransmission of the epididymal portion of rat vas deferens has been investigated. This drug potentiated the electrically induced responses (46.6% +/- 5.09 at a concentration of 3.7 microM) and the contractile effect of exogenous noradrenaline with a concentration-dependent reduction of EC50 (from 0.99 +/- 0.11 microM to 0.06 +/- 0.01 microM). Moreover, MK-801 alone induced spontaneous contractile responses that were abolished by prazosin, not reversed by N-methyl-D-aspartate (NMDA) + glycine and that did not appear in organs obtained from reserpinized rats. In addition, MK-801 inhibited the [3H]noradrenaline uptake in slices from rat vas deferens (IC50 = 1.79 +/- 0.06 microM). Since these effects took place in the presence of magnesium and were sodium-dependent, a direct participation of the NMDA receptor complex can be ruled out, pointing to the inhibition of the cathecolamine uptake systems in the postganglionic sympathetic nerve endings as the most feasible mechanism.
authors.affiliation: Laboratory of Pharmacology and Pharmacognosy, Faculty of Pharmacy, University of Barcelona, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Pubill
authors.forename: A M
authors.initials: AM
authors.lastname: Canudas
authors.forename: D
authors.initials: D
authors.lastname: Gasulla
authors.forename: M
authors.initials: M
authors.lastname: Pallàs
authors.forename: E
authors.initials: E
authors.lastname: Escubedo
authors.forename: J
authors.initials: J
authors.lastname: Camarasa
mesh_terms: D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D010622:Phencyclidine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects*; D014649:Vas Deferens / Q000187:drug effects* / Q000378:metabolism
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016291:Dizocilpine Maleate; D010622:Phencyclidine; D009638:Norepinephrine