Cardiovascular research
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Cardiovascular research · Sep 1995
Comparative StudyMyocardial interstitial purine metabolites and lactate with increased work in swine.
Dobutamine stimulates the beta-receptors in the heart and increases myocardial blood flow and oxygen consumption 2-3-fold, similar to effects seen with exercise. The purpose of this study was to assess temporal changes in myocardial interstitial purine metabolites, adenosine monophosphate (AMP) and lactate during and following 30 min of dobutamine infusion. ⋯ The dobutamine-induced increases in myocardial oxygen consumption, rate x pressure product, and blood flow, without an increase in coronary venous or interstitial lactate suggest that energy balance is maintained during dobutamine infusion. Thus an increase in myocardial work, in the absence of demand-induced ischemia, resulted in accumulation of adenosine and AMP in the interstitium.
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Cardiovascular research · Sep 1995
Inhibition of nitric oxide synthesis protects the isolated working rabbit heart from ischaemia-reperfusion injury.
Nitric oxide (NO) exerts both protective and detrimental actions in a variety of biological systems. During acute reperfusion following myocardial ischaemia, a rapid overproduction of free radicals, including NO, may occur. We investigated the effects of the NO synthase inhibitors NG-nitro-L-arginine methyl ester (L-NAME) and NG-monomethyl-L-arginine (L-NMMA), and the substrate for NO synthesis, L-arginine, on heart function during ischaemia and reperfusion injury. ⋯ These results suggest that: (1) the recovery of mechanical function of hearts subjected to ischaemia-reperfusion injury can be improved by modulation of myocardial NO synthesis, (2) inhibition of NO synthesis (with L-NAME or L-NMMA) may offer prolonged protection whereas its stimulation (with L-arginine) provides only brief protection, and (3) the reasons for the pharmacological effectiveness of these divergent strategies may be due to the formation of peroxynitrite from NO and superoxide anion during reperfusion.