Methionine-enkephalin and morphine: amount ejected microiontophoretically.
The microiontophoretic transport numbers of Met-enkephalin and morphine were determined by ejecting the tritiated compounds from both 5-barrel and 7-barrel micro-pipettes into a small volume of 0.9% NaCl, using a series of ejection currents and various timed durations. The transport number of Met-enkephalin was 2-4 times less than that for morphine in 5- and 7-barrel pipettes. The transport numbers of both drugs in 5-barrel pipettes were significantly greater than those in 7-barrel pipettes. These results indicate the need for caution in comparing the data derived from different studies that use microiontophoresis. The transport numbers for morphine and Met-enkephalin were used to compare the effects of these agents on neuronal firing.
D000818:Animals; D001692:Biological Transport; D004723:Endorphins / Q000494:pharmacology*; D004744:Enkephalin, Methionine; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D007478:Iontophoresis / Q000379:methods; D007700:Kinetics; D008845:Microinjections / Q000379:methods; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D014316:Tritium
D004723:Endorphins; D004745:Enkephalins; D014316:Tritium; D004744:Enkephalin, Methionine; D009020:Morphine