Possible inhibition of Ca++ pump of rat erythrocyte ghosts by opioid k agonists.
Rat erythrocyte ghosts containing 45Ca++, EGTA, ATP and Pipes buffer (pH 7.2) were prepared for studying opioid effects on Ca++ flux. Ethylketocyclazocine and dynorphin 1-13 (dynorphin) dose-dependently inhibited La+++-sensitive outward 45Ca++ movement at nM concentrations and the effect was naloxone reversible. Morphine and beta-endorphin were also effective at higher concentrations, whereas levorphanol and leu-enkephalin were ineffective. None of the opioids studied inhibited 45Ca++ inward movement. Based on these findings, it is concluded that rat erythrocyte possesses k-type opioid receptors through which the Ca++-pump may be inhibited.
D000818:Animals; D002118:Calcium / Q000097:blood*; D000252:Calcium-Transporting ATPases / Q000097:blood; D004723:Endorphins / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*; D017473:Receptors, Opioid, kappa
D004723:Endorphins; D009294:Narcotics; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D000252:Calcium-Transporting ATPases; D002118:Calcium