The effect of opioids and of naloxone on Na+,K+-adenosine triphosphatase activity in frog spinal cord membrane fractions.
The effects of opioids and of naloxone on ouabain-sensitive Na+,K+-adenosine triphosphatase (ATPase) activity were studied in vitro on membrane fractions from frog spinal cords. The addition of morphine and of the stable enkephalin analogue, D-Ala2,D-Leu5-enkephalin, in concentrations from 10(-7) to 10(-4) M significantly increased Na+,K+-ATPase activity. No effect was found with methionine enkephalin (Met-Enk). However, the addition of two peptidase inhibitors, captopril and phosphoramidon (10(-5) M each), significantly increased Na+,K+-ATPase activity. A further increase in enzyme activity was found when Met-Enk (10(-4) or 10(-7) M) was added simultaneously with peptidase inhibitors. On the other hand, the addition of the opiate antagonist, naloxone, at low concentration (10(-7) M) decreased the activity of Na+,K+-ATPase. These results are discussed with respect to the effect of synthetic and endogenous opioids on the activity of Na+,K+-ATPase.
D000818:Animals; D002216:Captopril / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology; D006020:Glycopeptides / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology*; D011896:Rana temporaria; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology* / Q000201:enzymology
D004723:Endorphins; D004745:Enkephalins; D006020:Glycopeptides; D009270:Naloxone; D009020:Morphine; D002216:Captopril; D000254:Sodium-Potassium-Exchanging ATPase; C008890:phosphoramidon