Islet-activating protein (pertussis toxin) diminishes alpha 2-adrenoceptor mediated effects on noradrenaline release.
The effect of islet-activating protein (IAP) on alpha 2-adrenoceptor mediated modulation of noradrenaline release in the rabbit hippocampus was studied. Slices of the hippocampus were incubated for 6 h with IAP, subsequently loaded with 3H-noradrenaline and superfused continuously. IAP-pretreatment significantly enhanced the electrically evoked transmitter release and diminished the facilitatory effect of the alpha 2-adrenoceptor antagonist yohimbine. In addition, the inhibitory effect of the alpha 2-adrenoceptor agonist clonidine was reduced. These results provide circumstantial evidence that an inhibitory guanine-nucleotide-binding protein, most probably Ni of a presynaptically located adenylate cyclase, is involved in the alpha 2-autoreceptor mediated modulation of noradrenaline release.
D037361:Adenylate Cyclase Toxin; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology; D004558:Electric Stimulation; D006386:Hemagglutination Tests; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000378:metabolism*; D037342:Pertussis Toxin; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D011942:Receptors, Adrenergic, alpha; D010566:Virulence Factors, Bordetella; D015016:Yohimbine; D000242:Cyclic AMP; D037342:Pertussis Toxin; D003000:Clonidine; D009638:Norepinephrine