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The aim of this review is to provide basic information on the electrophysiological changes during acute ischemia and reperfusion from the level of ion channels up to the level of multicellular preparations. After an introduction, section II provides a general description of the ion channels and electrogenic transporters present in the heart, more(More)
1. We have investigated whether Ca2+ entry through T-type Ca2+ channels participates in triggering Ca2+ release from the sarcoplasmic reticulum (SR) in single guinea-pig ventricular myocytes (whole-cell voltage clamp, K5fura-2 as [Ca2+]i indicator; all monovalent cations replaced by impermeant ions to record uncontaminated Ca2+ currents; T = 23 or 36(More)
The delayed K+ current (ik) and its change by dofetilide was studied in single myocytes from the guinea pig and rabbit heart using the two-electrode voltage clamp technique. In rabbit myocytes, ik consisted of only one component (Kr), which developed for moderate depolarizations and with a fast time course. In guinea pig myocytes, activation consisted of a(More)
Single-channel measurements and whole-cell experiments with the two suction electrode, voltage clamp technique were used to investigate the effects of external and internal proton concentrations on T-type Ca channels in heart muscle cells of the guinea pig. As in the L-type Ca channel, an increase in the external proton concentration decreases T-type(More)
Voltage clamp analysis of the transient outward (positive dynamic) current was performed in sheep Purkinje fibers at a pulse frequency of 1/min. 4-aminopyridine (4-AP, 1 mM) suppressed most of the transient outward current, thus revealing the slow inward current, isi, and an associated brief outward current ibo. The long lasting component of the current(More)
1. Single Purkinje cells, enzymatically isolated from rabbit ventricle, were studied under whole-cell voltage clamp and internally perfused with the fluorescent Ca2+ indicator, indo-1 (100 microM). 2. Fast [Ca2+]i transients were elicited by brief depolarizations from a holding voltage of -45 mV and by repolarization from very positive potentials. The peak(More)
The time course of the inward-rectifying K current during hyperpolarizing clamp steps was investigated in single myocytes isolated from guinea-pig ventricles. The experiments were done using a two-electrode voltage-clamp technique with two patch pipettes in the whole-cell configuration. Hyperpolarizations to potentials negative to -100 mV, induced large(More)
Single Purkinje cells from dog, sheep and cow hearts were isolated by injecting a Ca-free collagenase containing Tyrode solution in the space between the connective tissue sheath and the Purkinje cells. A small proportion of these cells survived the isolation procedure and these cells were used for further investigation. The cells showed(More)
We have investigated the modulation of the L-type Ca2+ channel by Ca2+ released from the sarcoplasmic reticulum (SR) in single guinea pig ventricular myocytes under whole-cell voltage clamp. [Ca2+]i was monitored by fura 2. By use of impermeant monovalent cations in intracellular and extracellular solutions, the current through Na+ channels, K+ channels,(More)
The Na(+)-activated K+ current was studied in inside-out patches and in whole cells isolated from the guinea-pig cardiac ventricle. The single channel conductance showed inward rectification for K+i less than K+e, but outward rectification for K+i greater than K+e. The open probability was dependent on Na+i and Na+,K(+)-pump activity. In the presence of(More)