Role of oxidative metabolism on endothelium-dependent vascular relaxation of isolated vessels.
The obligatory role of endothelium in mediating vasodilator response to numerous humoral agents has been definitely accepted. However, the chemical identity of endothelium-derived relaxing factor(s) (EDRF) and the mechanisms underlying its synthesis and release remain unclear. Much evidence suggests a compartmentalization of ATP into cells, such that ATP derived from glycolysis or from oxidative metabolism is used for different cellular functions. To investigate which energy source (i.e. oxidative v glycolytic metabolism) is preferentially used for the biosynthesis and/or release of EDRF, rings of rabbit thoracic aorta were studied in organ chambers. After preconstriction with PGF2 alpha, inhibition of glycolysis with either iodoacetate (300 microM) (n = 6) or 2-deoxyglucose (20 mM) (n = 6) did not affect concentration-response curve to the endothelium-dependent agent acetylcholine. In contrast, inhibition of oxidative metabolism with either 1 mM amytal or 5 microM rotenone markedly impaired relaxation to acetylcholine. In fact, maximal relaxation was 75 +/- 5% in control rings (n = 6), and 42 +/- 7% (P < 0.01) in amytal-treated rings (n = 6), whereas rotenone converted acetylcholine relaxation into constriction (n = 6; P < 0.001). The effect of amytal on endothelium-dependent relaxation was reversible, suggesting that endothelial cells were not damaged by the inhibitor. Amytal also markedly reduced endothelium-mediated relaxation to ADP (37 +/- 6%; P < 0.05; n = 5), as well as to the calcium ionophore A23187. Neither mitochondrial inhibitor affected relaxation to nitroglycerin, an endothelium-independent agent. Finally, amytal did not affect relaxation to S-nitrosocysteine (a recently proposed EDRF) (n = 5), suggesting that the effects on acetylcholine and ADP responses were not due to non-specific interferences with EDRF once released from endothelial cells. In conclusion, our data demonstrate that the active process of biosynthesis and/or release of EDRF requires energy derived mainly from mitochondrial oxidative metabolism.
Cappelli-Bigazzi
M
M
Division of Cardiology, Federico II School of Medicine, Naples, Italy.
Battaglia
C
C
Pannain
S
S
Chiariello
M
M
Ambrosio
G
G
D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000654:Amobarbital / Q000494:pharmacology; D000818:Animals; D001011:Aorta; D000001:Calcimycin / Q000494:pharmacology; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D003847:Deoxyglucose / Q000494:pharmacology; D015237:Dinoprost / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects; D004730:Endothelium, Vascular / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects / Q000502:physiology*; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology; D009924:Organ Culture Techniques; D010084:Oxidation-Reduction; D011817:Rabbits; D012402:Rotenone / Q000494:pharmacology; D026403:S-Nitrosothiols; D014475:Uncoupling Agents / Q000494:pharmacology; D014664:Vasodilation / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D007461:Iodoacetates; D007476:Ionophores; D026403:S-Nitrosothiols; D014475:Uncoupling Agents; D014665:Vasodilator Agents; D012402:Rotenone; D009569:Nitric Oxide; D000001:Calcimycin; D000255:Adenosine Triphosphate; C021315:S-nitrosocysteine; D003847:Deoxyglucose; D015237:Dinoprost; D005996:Nitroglycerin; D000654:Amobarbital; D003545:Cysteine; D000109:Acetylcholine; D019807:Iodoacetic Acid