Nitric oxide induced contractile dysfunction is related to a reduction in myocardial energy generation
Küçük Resim Yok
Tarih
1997
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Science Bv
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Objective: It has been suggested that nitric oxide (NO) is involved in the regulation of myocardial function in a variety of diseases such as dilated cardiomyopathy, myocarditis, heart transplant rejection, and septic shock. However, the underlying mechanism of NO mediated reduction of cardiac contractility has not been clearly established so far. Therefore, we studied the effects of authentic NO on left ventricular function and myocardial energy status in the isolated heart. Methods: In 43 isolated perfused guinea pig hearts quantitative and kinetic changes in coronary flow (CF), left ventricular developed pressure (LVDP), the cardiac release of adenosine, lactate, cyclic GMP, and norepinephrine were measured during infusion of authentic NO. In parallel, myocardial phosphocreatine (PCr), ATP and the free energy change of ATP-hydrolysis (Delta G(ATP)) were measured using P-31 nuclear magnetic resonance spectroscopy. Results: At low concentrations (0.01 to 1.0 mu mol/L) NO increased CF only; at higher concentrations (1 to 100 mu mol/L) CF remained elevated and LVDP was significantly reduced. Onset and offset of changes in LVDP occurred always within 2 to 5 a after start and cessation of NO infusion. Contractile dysfunction was significantly correlated to a pronounced increase in adenosine formation (>70-fold), a significant decrease in myocardial PCr (-78%), ATP (-25%) and a decrease in Delta G(ATP) from -61.76 kJ/mol to -50.75 kJ/mol. This was paralleled by a significant decrease in myocardial oxygen consumption (-65%) and a tenfold increase in lactate production. Coronary vasodilation (NO: 0.001 to 1.0 mu mol/L) significantly correlated with the increase in cGMP release, whereas at negative inotropic concentrations (NO: 10 to 100 mu mol/L) a clear quantitative and kinetic dissociation between NO-induced changes in cGMP and LVDP was observed, Contractile dysfunction was not related to cardiac release of norepinephrine. Conclusions: In the isolated heart NO can potently depress myocardial energy generation thus being an effective modulator of cardiac contractility, This effect of NO may be of pathophysiological significance in cardiac muscle disorders in vivo. (C) 1997 Elsevier Science B.V.
Açıklama
Anahtar Kelimeler
endothelium-derived factors (nitric oxide), free radicals, myocardial contraction, guinea pig
Kaynak
Cardiovascular Research
WoS Q Değeri
Q1
Scopus Q Değeri
N/A
Cilt
36
Sayı
2
