Protein kinase C and alpha 2-adrenoceptor-mediated inhibition of noradrenaline release from the rat tail artery.
In isolated rat tail arteries preincubated with [3H]noradrenaline, electrical field stimulation evoked the overflow of tritium. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activating phorbol ester, time-dependently increased the overflow at 1 mumol/L but not at 0.1 mumol/L. In contrast, the overflow was not altered by phorbol 13-acetate (PA, 1 mumol/L), which does not influence the activity of PKC. Polymyxin B (70 mumol/L), an inhibitor of PKC, depressed the overflow when given alone and, in addition, attenuated the effect of PMA, 1 mumol/L. The selective alpha 2-adrenoceptor agonist B-HT 933 depressed the overflow; PMA, 1 mumol/L, did not interfere with the effect of B-HT 933, 10 mumol/L. The results provide evidence for the participation of prejunctionally located PKC in the release of noradrenaline. However, PKC does not seem to be involved in the alpha 2-adrenoceptor-agonist-mediated inhibition of noradrenaline release.
Bucher
B
B
Laboratoire de Pharmacologie Cellulaire et Moléculaire, C.N.R.S. URA 600, Université Louis Pasteur Strasbourg, Illkirch, France.
Neuburger
J
J
Illes
P
P
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000294:innervation / Q000378:metabolism; D001381:Azepines / Q000494:pharmacology; D004789:Enzyme Activation; D008297:Male; D009474:Neurons / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D013623:Tail / Q000098:blood supply* / Q000294:innervation; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014316:Tritium
D000316:Adrenergic alpha-Agonists; D001381:Azepines; D011942:Receptors, Adrenergic, alpha; D014316:Tritium; C015603:azepexole; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D009638:Norepinephrine