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Opioids stimulate sarcolemmal NAD(P)H-vanadate dehydrogenase activity
C Ventura1, C Guarnieri, L Bastagli
1Department of Biochemistry, University of Bologna, Italy.
Basic Research in Cardiology
|July 1, 1988
Summary
Bovine cardiac sarcolemma exhibits NAD(P)H dehydrogenase activity, influenced by opioid receptor agonists like methionine-enkephalin and dynorphin A. This activity is modulated by specific inhibitors and receptor antagonists, revealing novel biochemical pathways.
Area of Science:
- Biochemistry
- Cardiovascular Physiology
- Pharmacology
Background:
- The bovine cardiac sarcolemma exhibits enzymatic activities crucial for cellular function.
- NAD(P)H dehydrogenases play a role in cellular redox balance and energy metabolism.
- Opioid receptors are known to modulate various physiological processes, including cardiovascular function.
Purpose of the Study:
- To investigate the presence and characteristics of NAD(P)H dehydrogenase activity in bovine cardiac sarcolemma.
- To determine the effect of opioid receptor agonists (methionine-enkephalin and dynorphin A) on this dehydrogenase activity.
- To explore the involvement of specific inhibitors and receptor antagonists in modulating the observed enzymatic and opioid-induced activities.
Main Methods:
- Enzymatic assays were performed on isolated bovine cardiac sarcolemma.
- NAD(P)H and NADH oxidation rates were measured using vanadate as an electron acceptor.
- The effects of inhibitors (superoxide dismutase, atebrin, 2,4-dinitrophenol) and opioid receptor agonists/antagonists (methionine-enkephalin, dynorphin A, naloxone, Mr 1452) were evaluated.
Main Results:
- Bovine cardiac sarcolemma possesses NAD(P)H dehydrogenase activity, with higher NADH than NAD(P)H oxidation.
- This activity was inhibited by superoxide dismutase, atebrin, and 2,4-dinitrophenol.
- Opioid receptor agonists dose-dependently increased NAD(P)H dehydrogenase activity, with dynorphin A being more potent than methionine-enkephalin at lower concentrations.
- Inhibitors and receptor antagonists differentially modulated the opioid-stimulated activity, indicating receptor-specific interactions.
Conclusions:
- Bovine cardiac sarcolemma exhibits significant NAD(P)H dehydrogenase activity sensitive to redox modulators.
- Opioid receptor agonists modulate this sarcolemmal dehydrogenase activity in a dose-dependent and receptor-specific manner.
- These findings suggest a potential role for opioid signaling in regulating cardiac sarcolemmal redox status and enzymatic function.