Role of endogenous opioids in ischemic preconditioning but not in short-term hibernation in pigs.

Abstract

Endogenous opioids are involved in ischemic preconditioning (IP) in several species. Whether or not opioids are important for IP and short-term myocardial hibernation (STMH) in pigs is currently unknown. In 34 enflurane-anesthetized pigs, the left anterior descending coronary artery was flow constantly perfused. Subendocardial blood flow (Endo), infarct size (IS; percent area at risk), and the free energy change of ATP hydrolysis (DeltaG) were determined. After 90-min severe ischemia and 120-min reperfusion, IS averaged 28.3 +/- 5.4% (means +/- SE) (n = 8; Endo: 0.047 +/- 0.009 ml. min(-1) x g(-1)). IP by 10-min ischemia and 15-min reperfusion reduced IS to 9.9 +/- 3.8% (P < 0.05, n = 8; Endo: 0.044 +/- 0.009 ml. min(-1) x g(-1)). After naloxone (1 mg/kg iv followed by 2 microg x kg(-1) x min(-1)), IS averaged 25.8 +/- 7.0% (n = 6; Endo: 0.039 +/- 0.008 ml x min(-1) x g(-1)) without and 24.7 +/- 4.7% (n = 6; Endo: 0.044 +/- 0.006 ml x min(-1) x g(-1)) with IP. At 5-min moderate ischemia in the presence of naloxone, Endo decreased from 0.90 +/- 0.07 to 0.28 +/- 0.03 ml x min(-1) x g(-1)and DeltaG decreased from -58.6 +/- 1.0 to -52.6 +/- 0.4 kJ/mol. Prolongation of ischemia to 90 min did not alter Endo, but DeltaG recovered toward control values (57.7 +/- 1.1 kJ/mol), and the myocardium remained viable. These responses are identical to those of nonnaloxone-treated pigs. Endogenous opioids are involved in IP but not in STMH in pigs.

• Authors: R Schulz, P Gres, G Heusch
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 280 Issue 5 Pg. H2175-81 (May 2001) ISSN: 0363-6135 [Print] United States
• PMID: 11299219 (Publication Type: Journal Article)

Chemical References

• Narcotic Antagonists
• Opioid Peptides
• Naloxone
• Adenosine Triphosphate

Topics

• Adenosine Triphosphate (metabolism)
• Animals
• Coronary Circulation (drug effects, physiology)
• Disease Models, Animal
• Energy Metabolism (drug effects, physiology)
• Female
• Ischemic Preconditioning, Myocardial
• Male
• Myocardial Infarction (pathology, physiopathology)
• Myocardial Stunning (pathology, physiopathology)
• Myocardium (metabolism, pathology)
• Naloxone (pharmacology)
• Narcotic Antagonists (pharmacology)
• Opioid Peptides (physiology)
• Swine, Miniature
• Time Factors