Effect of 6-hydroxydopamine on [3H]-adenine nucleotide and [3H]-noradrenaline release from the guinea-pig taenia caecum evoked by electrical field stimulation, nicotine and perivascular nerve stimulation.
1 The effects of pretreatment of guinea-pigs with 6-hydroxydopamine (6-OHDA) on the release of [(3)H]-noradrenaline and [(3)H]-adenine nucleotide following electrical field, nicotine and perivascular nerve stimulation of guinea-pig taenia caecum were studied.2 High frequency electrical field stimulation (15,30 Hz) released both [(3)H]-noradrenaline and [(3)H]-adenine nucleotide but low frequency (0.5, 5 Hz) stimulation, producing comparable muscle relaxation led only to [(3)H]-noradrenaline release.3 6-OHDA (50-200 mg/kg) pretreatment inhibited the muscle relaxation and [(3)H]-noradrenaline release with electrical stimulation or with nicotine in isolated taenia but did not affect the release of [(3)H]-nucleotide.4 A low dose of 6-OHDA (50 mg/kg), completely inhibited the muscle relaxation and [(3)H]-noradrenaline release elicited by perivascular nerve stimulation.5 Both tissue noradrenaline content and [(3)H]-noradrenaline uptake were decreased to the same extent by low as well as high doses of 6-OHDA: noradrenaline content was reduced to 20% and uptake to 30% of the control value.6 Catecholamine fluorescence disappeared from tissue layers of the taenia after treatment with a high dose of 6-OHDA.7 In these experiments the inhibitory action of electrical stimulation and nicotine on the taenia can be correlated better with noradrenaline than with nucleotide release.
D000227:Adenine Nucleotides / Q000378:metabolism*; D000818:Animals; D002432:Cecum / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D006168:Guinea Pigs; D006651:Histocytochemistry; D006892:Hydroxydopamines / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D013268:Stimulation, Chemical; D013562:Sympathectomy; D013997:Time Factors; D014316:Tritium
D000227:Adenine Nucleotides; D006892:Hydroxydopamines; D014316:Tritium; D009538:Nicotine; D009638:Norepinephrine