Kappa-opiate binding to rat brain and guinea pig cerebellum: sensitivity towards ions and nucleotides.
Sodium ions and guanine nucleotides markedly affect the binding to mu and delta sites. Using the guinea pig cerebellum, a tissue whose opioid binding sites are almost exclusively kappa, we have examined the sensitivity of [3H](-)-ethylketocyclazocine ([3H]EKC) binding to ions and guanine nucleotides. Unlike mu and delta binding, sodium ions and guanine nucleotides had little effect on the [3H]EKC binding in the guinea pig cerebellum. On the other hand, calcium and manganese at 1 mM lowered [3H]EKC binding in the guinea pig cerebellum by approximately 25%. Binding in rat brain, which was primarily mu and delta, was unaffected. These results point out additional biochemical differences between kappa sites and the classic mu and delta binding sites.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000378:metabolism; D004573:Electrolytes / Q000494:pharmacology*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D004745:Enkephalins / Q000494:pharmacology; D016314:Ethylketocyclazocine; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006168:Guinea Pigs; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa
D004573:Electrolytes; D004745:Enkephalins; D006150:Guanine Nucleotides; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D016314:Ethylketocyclazocine; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D003496:Cyclazocine