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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Analgesics, Opioid, Animals, Body Weight, Hemodynamics, Indoles, Ischemic Preconditioning, Myocardial, Male, Mitochondria, Morphine, Myocardial Infarction, Myocardial Reperfusion Injury, Organ Size, Potassium Channel Blockers, Potassium Channels, Calcium-Activated, Rats, Rats, Wistar.
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Does morphine induce preconditioning via activation of mitochondrial K ( Ca ) channels? Context: Mitochondrial calcium sensitive potassium (mK(Ca)) channels are involved in cardioprotection induced by ischemic preconditioning. In the present study we investigated whether morphine-induced preconditioning also involves activation of mK(Ca) channels. Isolated rat hearts (six groups; each n = 8) underwent global ischemia for 30 min followed by a 60-min reperfusion. Control animals were not further treated. Morphine preconditioning (MPC) was initiated by two five-minute cycles of morphine 1 microM infusion with one five-minute washout and one final ten-minute washout period before ischemia. The mK(Ca) blocker, paxilline 1 microM, was administered, with and without morphine administration (MPC + Pax and Pax). As a positive control, we added an ischemic preconditioning group (IPC) alone and combined with paxilline (IPC + Pax). At the end of reperfusion, infarct sizes were determined by triphenyltetrazoliumchloride staining. Infarct size was (mean +/- SD) 45 +/- 9% of the area at risk in the Control group. The infarct size was less in the morphine or ischemic preconditioning groups (MPC: 23 +/- 8%, IPC: 20 +/- 5%; each P < 0.05 vs Control). Infarct size reduction was abolished by paxilline (MPC + Pax: 37 +/- 7%, P < 0.05 vs MPC and IPC + Pax: 36 +/- 6%, P < 0.05 vs IPC), whereas paxilline alone had no effect (Pax: 46 +/- 7%, not significantly different from Control).
assistant
Cardioprotection by morphine-induced preconditioning is mediated by activation of mK(Ca) channels. Final Decision: yes