title: Opioids, noradrenaline and GTP analogs inhibit cholera toxin activated adenylate cyclase in neuroblastoma x glioma hybrid cells.
abstract: D-Ala2-Met5-enkephalin, morphine, and noradrenaline inhibit the adenylate cyclase in homogenates of neuroblastoma x glioma hybrid cells in a dose-dependent manner even after the enzyme has been preactivated by cholera toxin. Half-maximal inhibition and extent of inhibition are the same with native or cholera toxin-activated enzyme. The inhibition caused by opioids or noradrenaline are antagonized by naloxone or phentolamine, respectively. The effect of D-Ala2-Met5-enkephalin on cholera toxin-activated enzyme is immediate in onset and rapidly reversed by the addition of naloxone. Guanyl-5'-yl-imidodiphosphate stimulates basal activity but inhibits the enzyme activated by cholera toxin or prostaglandin E1. Stimulation occurs at a concentration of 100 microM or above, inhibition even at 0.1 microM. The inhibitory effect of the non-hydrolysable GTP analog is antagonized by GTP. Guanyl-5'-yl-methylenediphosphonate, another nonhydrolysable GTP analog, inhibits basal as well as cholera toxin-stimulated or prostaglandin E1-stimulated adenylate cyclase. Other guanine derivatives such as GDP, GMP, cyclic GMP, guanyl-5'-yl-phosphoric acid amide and guanosine have no effect under the same conditions. The results may be taken as a piece of evidence for two separate guanyl nucleotide-binding sites accompanying the adenylate cyclase in the hybrid cells and mediating, respectively, stimulation and inhibition of the enzyme by hormones.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology*; D002999:Clone Cells; D004164:Diphosphonates / Q000494:pharmacology; D004723:Endorphins / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives*; D004745:Enkephalins / Q000494:pharmacology*; D005910:Glioma; D006157:Guanosine Monophosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006822:Hybrid Cells / Q000201:enzymology*; D007700:Kinetics; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009447:Neuroblastoma; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats
chemical_list: D004164:Diphosphonates; D004723:Endorphins; D004745:Enkephalins; D006165:Guanylyl Imidodiphosphate; C004805:5'-guanylylmethylenebisphosphonate; D004744:Enkephalin, Methionine; C013801:enkephalin-Met, Ala(2)-; D009020:Morphine; D006157:Guanosine Monophosphate; D006160:Guanosine Triphosphate; D002772:Cholera Toxin; D000262:Adenylyl Cyclases; D009638:Norepinephrine