Mu-receptor binding in physiological media: comparison with isolated tissue data.
Mu-receptor affinities have been determined for a number of opioid drugs using a combination of isolated tissue and receptor binding techniques. The affinities of antagonists and partial agonists were determined by their ability to antagonise responses to [D-Ala2,MePhe4,Glyol5]enkephalin (GLYOL) on the rat vas deferens preparation. There was little correlation between these results and affinities measured by displacement of [3H]-GLYOL from guinea-pig brain membranes incubated in 50mM Tris buffer. By contrast, affinities measured by displacement of [3H]-naloxone from rat brain membranes incubated in a Krebs/HEPES buffer containing a non-hydrolysable analogue of GTP, agreed very closely with the isolated tissue data.
D000818:Animals; D001921:Brain / Q000378:metabolism; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009270:Naloxone / Q000378:metabolism; D009294:Narcotics / Q000378:metabolism; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism*; D017450:Receptors, Opioid, mu; D014649:Vas Deferens / Q000378:metabolism
D004745:Enkephalins; D009294:Narcotics; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone