Electrophysiologic effects of exogenous phosphocreatine in cardiac tissue: potential antiarrhythmic actions

High-Energy Phosphates and Ischemic Heart Disease: From Bench to Bedside

The purpose of this review is to bridge the gap between clinical and basic research through providing a comprehensive and concise description of the cellular and molecular aspects of cardioprotective mechanisms and a critical evaluation of the clinical evidence of high-energy phosphates (HEPs) in ischemic heart disease (IHD). According to the well-documented physiological, pathophysiological and pharmacological properties of HEPs, exogenous creatine phosphate (CrP) may be considered as an ideal metabolic regulator. It plays cardioprotection roles from upstream to downstream of myocardial ischemia through multiple complex mechanisms, including but not limited to replenishment of cellular energy. Although exogenous CrP administration has not been shown to improve long-term survival, the beneficial effects on multiple secondary but important outcomes and short-term survival are concordant with its pathophysiological and pharmacological effects. There is urgent need for high-quality multicentre RCTs to confirm long-term survival improvement in the future.

Risk stratification of in-hospital mortality in patients hospitalized for chronic congestive heart failure secondary to non-ischemic cardiomyopathy

The study population consisted of 234 consecutive patients hospitalized for acute exacerbation of congestive heart failure secondary to non-ischemic cardiomyopathy. Of the 234 patients, there were 55 in-hospital deaths. Their medical records were deliberatively reviewed and the association of 38 clinical, hemodynamic and biochemical variables with in-hospital mortality was evaluated by multiple stepwise logistic regression analysis. The following variables were statistically associated with in-hospital mortality: profound cardiogenic shock, severe hyponatremia, the presence of ventricular arrhythmias, history of stroke, the presence of acute renal failure, and requirement of dobutamine therapy. In stratified analyses, the rates of in-hospital mortality rose rapidly as the number of risk factors increased: 0 risk factors, 2.5%; 1 risk factor, 5.1%; 2 risk factors, 36.4%; 3 risk factors, 75%, and no less than 4 risk factors, 100%. In conclusion, our study identified 6 variables that correlated with in-hospital death in patients with heart failure secondary to non-ischemic cardiomyopathy. The identification of these variables may allow more accurate risk stratification of individuals at risk of in-hospital mortality in this clinical setting.

The effects of phosphocreatine introduced simultaneously into many cardiac cells

The aim of the present study was to ascertain whether or not phosphocreatine (PC) could produce electrophysiological and inotropic effects in isolated rabbit cardiac preparations. Exogenous PC (50 mmol/l) was introduced into many cells simultaneously by the "cut-end" and "saponinated-end" methods. PC that entered the cells (opened by cutting or chemical disruption of the sarcolemma) in the loading region, passed through the preparation intercellularly and evoked the following effects in the test region. PC enhanced the spontaneous rate and probably shifted the pacemaker in sinus node strips. On the other hand, PC elevated the action potential amplitude and duration and increased the isometric tension in atrial and ventricular strips. Furthermore, PC applied into ventricular cells partially prevented the effects of hypoxia. These findings suggest that PC may act in cardiac muscle as an intercellular energy carrier. The effects of PC introduced intracellularly resembled these evoked by O-benzyl-phosphocreatine--a permanent synthetic phosphagen--applied via superfusion.

Effects of high-energy phosphates on carbachol-evoked cationic current in single smooth muscle cells from guinea-pig ileum

1. Single smooth muscle cells from the longitudinal muscle layer of guinea-pig small intestine were voltage clamped in the whole-cell recording mode with patch pipettes. The cationic current (Icat) evoked by application of 50 microM carbachol (CCh) was examined when free internal calcium in the cell was 'clamped' at 10(-7) M with 20 mM BAPTA. The effects of varying the composition of the pipette solution were studied. 2. Phosphocreatine (PCr, 6 mM) added to the pipette solution increased Icat by about 7-fold (to near 620 pA); lower concentrations had similar, generally lesser, effects. Na2ATP (3 or 6 mM) with or without 5 mM MgCl2 was much less effective than phosphocreatine alone. Addition of 3 mM Na2ATP reduced Icat, whether or not phosphocreatine was present. 3. Creatine (6 mM) with or without 2 mM Na2ATP was less effective than phosphocreatine in maintaining Icat. 4. GTP (0.1 mM) did not affect Icat evoked by CCh, whether phosphocreatine was present or not. 5. GTP gamma S (0.2 mM) included in pipette solution mimicked the effect of CCH and evoked Icat independently of whether PCr was present or not in the pipette solution. Including 5 mM ATP in the pipette reduced this current, whereas 5'-adenylyl imidodiphosphate (AMP-PNP) and ADP were without effect. 6. The results show that phosphocreatine increases membrane channel responsiveness to receptor activation and that ATP above 2 mM suppresses it.