Release of methionine-enkephalin immunoreactivity from the rat spinal cord in vivo.
The spinal cord was superfused in situ, in the chloralose-urethanized rat. Radioimmunoassay for methionine-enkephalin-like activity revealed that the basal levels of release were on the order of 0.4 ng/ml/10 min. Addition of potassium (40 mM) to the perfusate yielded a 3-fold increase in the levels of MEI. This increase was blocked by the substitution of cobalt for calcium in the superfusate. These data suggest that MEI activity in the cord is stored in a releasible fraction and provides in vivo support for the concept that methionine-enkephalin is a neurotransmitter in the cord.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D004723:Endorphins / Q000378:metabolism*; D004744:Enkephalin, Methionine; D004745:Enkephalins / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
D004723:Endorphins; D004745:Enkephalins; D003035:Cobalt; D004744:Enkephalin, Methionine; D011188:Potassium; D002118:Calcium