Inhibitory action of opioid peptides on ouabain-sensitive Na+-K+ and Ca2+-dependent ATPase activities in bovine cardiac sarcolemma.
The present study demonstrates that morphine (10(-6) and 10(-5) M), methionine-enkephalin or leucine-enkephalin (10(-10), 10(-8), and 10(-6) M) were able to inhibit significantly, in a dose-dependent manner, both the sarcolemmal Ca2+-dependent ATPase and the ouabain-sensitive Na+-K+ ATPase activities. The inhibitory action of these opioids on the two ATPases was not antagonized by preincubation with naloxone (10(-6) M). Naloxone alone (10(-8), 10(-6) and 10(-5) M) did not affect both the sarcolemmal Ca2+-dependent ATPase and the ouabain-sensitive Na+-K+ ATPase activities. Heat-denatured methionine-enkephalin (10(-6) M) or leucine-enkephalin (10(-6) M) also unaffected both the ATPases. The possibility is also discussed that opioid peptides may regulate myocardial contractility by modulating the movement of ions across the heart sarcolemma.
Ventura
C
C
Muscari
C
C
Spampinato
S
S
Bernardi
P
P
Caldarera
C M
CM
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002417:Cattle; D004743:Enkephalin, Leucine / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D007700:Kinetics; D009020:Morphine / Q000494:pharmacology*; D009206:Myocardium / Q000201:enzymology*; D009270:Naloxone / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology*; D012508:Sarcolemma / Q000201:enzymology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
D009270:Naloxone; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D010042:Ouabain; D009020:Morphine; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase