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BACKGROUND To elucidate metabolic changes that occur in diabetes, obesity, and cancer, it is important to understand cellular energy metabolism pathways and their alterations in various cells. METHODOLOGY AND PRINCIPAL FINDINGS Here we describe a technology for simultaneous assessment of cellular energy metabolism pathways. The technology employs a redox(More)
1. The spontaneous electrical activity of small strips of muscle from the sinus venosus region of the heart of Rana catesbeiana was investigated using the double sucrose gap technique. The voltage clamp was used to record the ionic currents underlying the pace-maker depolarization and the action potential.2. The records of spontaneous electrical activity(More)
1. In atrial wall trabeculae of Rana catesbeiana and R. ridibunda very slowly decaying membrane currents have been consistently observed in decay tails following voltage clamp depolarizing and hyperpolarizing pulses. It is not thought that these currents are carried by time-dependent conductance channels but rather result from potassium ion accumulation or(More)
Atrial and ventricular myocytes were exposed to Ca(2+)- and K(+)-free solutions containing blockers of gated channel and exchange currents. Replacement of external sodium by large organic cations revealed a background sodium current ib,Na. In atrial cells, the average conductance was 5.0 pS pF-1. In ventricular cells the conductance was 2.3 pS pF-1.(More)
DiFrancesco & Noble's (1984) equations (Phil. Trans. R. Soc. Lond. B (in the press.] have been modified to apply to the mammalian sino-atrial node. The modifications are based on recent experimental work. The modified equations successfully reproduce action potential and pacemaker activity in the node. Slightly different versions have been developed for(More)
1. A double sucrose-gap voltage-clamp technique has been used to study the effects of acetylcholine on the membrane currents in atrial trabeculae of the bullfrog, Rana catesbeiana. 2. The second, or slow inward (Ca2+/Na+) current, was found to be markedly reduced by concentrations of acetylcholine greater than approximately 2-0 X 10(-8)M. The resulting(More)
1. A double sucrose gap method has been used to polarize and voltage clamp frog atrial muscle strips.2. In response to steady depolarizing currents, normally quiescent strips often show pace-maker activity, and long lasting depolarization occurs when the current is terminated.3. Voltage clamp experiments reveal the presence of two current components(More)
1. Slow inward tail currents attributable to electrogenic sodium-calcium exchange can be recorded by imposing hyperpolarizing voltage clamp pulses during the normal action potential of isolated guinea-pig ventricular cells. The hyperpolarizations return the membrane to the resting potential (between -65 and -88 m V) allowing an inward current to be(More)