Cultured embryonic chick heart cells: Photometric measurement of the cell pulsation and the effects of calcium ions, electrical stimulation and temperature,

Koidl, Bernd

doi:10.1016/0022-2828(80)90086-3

Cited by 19 publications

(4 citation statements)

References 26 publications

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“…With the average drift of action potential parameters in control recordings after 10 min (the time after which the effects due to Ba 2ϩ were measured) taken into account, MDP depolarizes by 5%, V max decreases by 13%, APA decreases by 7%, and IBI decreases by 9% (n ϭ 4) (79), whereas in the model, MDP depolarizes by 15%, V max decreases by 28%, APA decreases by 13%, and IBI decreases by 11%. However, the increases in APD and DDR in the experiments (12% increase in APD 50 and 28% increase in APD 90 ) are not replicated in the model. Because we have observed neither an increase in the peak I Ca nor slowed inactivation kinetics of I Ca with elevated Ba 2ϩ (79), we attribute the increase in APD in the experiments at least partially to rundown of I Ks , as we observed with almokalant (see Effect of Almokalant on Spontaneous Activity).…”

Section: Effect Of Ba 2ϩ On Spontaneous Activitymentioning

confidence: 92%

“…The resultant relative depolarization then causes I Ks to remain considerably more outward during the entire pacemaker potential and even during the early part of the action potential ( Fig. 10C shows I Ks time course during 100% I Kr block), which is the major cause of the decrease in APD 50 in Fig. 10B.…”

Section: Effect Of Almokalant On Spontaneous Activitymentioning

confidence: 99%

“…Because ϳ40% of our clusters do not beat (50), it is perhaps not surprising that there is a great deal of cluster-to-cluster variability in IBI and in the waveform of the action potential. It has been suggested that activity-dependent conductances might provide a negative-feedback mechanism by which spontaneous activity can be regulated (for review see Ref.…”

Section: Spontaneous Activity: Cell-to-cell Variability and Activity-mentioning

confidence: 99%

“…Ventricular myocytes were isolated from embryonic chick hearts by means of techniques previously described (50) with modifications (79). The hearts of 7-day embryos were removed, and the ventricles were chopped off, minced, and transferred to flasks containing 0.25% trypsin (bovine pancreas; Boehringer Mannheim, Deisenhofen, Germany) in a nominally Ca 2ϩ -and Mg 2ϩ -free Hanks' balanced salt solution (HBSS; in mM: 137 NaCl, 5.4 KCl, 0.34 Na2HPO4, 0.44 KH2PO4, 4.2 NaHCO3, and 5 glucose, pH 7.4).…”

Section: Cell Isolationmentioning

confidence: 99%

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An ionic model for rhythmic activity in small clusters of embryonic chick ventricular cells

Krogh‐Madsen

Schäffer²,

Skriver³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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We recorded transmembrane potential in whole cell recording mode from small clusters (2-4 cells) of spontaneously beating 7-day embryonic chick ventricular cells after 1-3 days in culture and investigated effects of the blockers D-600, diltiazem, almokalant, and Ba 2ϩ . Electrical activity in small clusters is very different from that in reaggregates of several hundred embryonic chick ventricular cells, e.g., TTX-sensitive fast upstrokes in reaggregates vs. TTX-insensitive slow upstrokes in small clusters (maximum upstroke velocity ϳ100 V/s vs. ϳ10 V/s). On the basis of our voltageand current-clamp results and data from the literature, we formulated a Hodgkin-Huxley-type ionic model for the electrical activity in these small clusters. The model contains a Ca 2ϩ current (ICa), three K ϩ currents (IKs, IKr, and IK1), a background current, and a seal-leak current. ICa generates the slow upstroke, whereas IKs, IKr, and IK1 contribute to repolarization. All the currents contribute to spontaneous diastolic depolarization, e.g., removal of the seal-leak current increases the interbeat interval from 392 to 535 ms. The model replicates the spontaneous activity in the clusters as well as the experimental results of application of blockers. Bifurcation analysis and simulations with the model predict that annihilation and single-pulse triggering should occur with partial block of I Ca. Embryonic chick ventricular cells have been used as an experimental model to investigate various aspects of spontaneous beating of cardiac cells, e.g., mutual synchronization, regularity of beating, and spontaneous initiation and termination of reentrant rhythms; our model allows investigation of these topics through numerical simulation.pacemaker; seal-leak current; rapid delayed rectifier potassium current block; slow inward calcium current block; bifurcation analysis SPONTANEOUS ACTIVITY based on generation of the pacemaker potential (spontaneous phase 4, or diastolic, depolarization) is not normally found in adult ventricular muscle in situ, nor is it normally found in single cells freshly isolated from adult ventricular muscle. In contrast, early enough during development, ventricular muscle (or areas of the heart destined to eventually become ventricular muscle) can beat spontaneously (1, 97). Spontaneous electrical activity can also be seen in single cells and in small clusters of cells isolated from the embryonic chick ventricle (10,17,26,49,51,78,95), in the embryonic mouse ventricle (117), and in the neonatal rat ventricle (86).After a couple of days in culture, the electrical activity in an isolated embryonic chick ventricular cell, in a small cluster of a few such cells, or in a sparse monolayer is very different from that in situ or in a reaggregate of hundreds or thousands of cells isolated from the ventricle. For example, when trypsin-dispersed ventricular cells from 7-day embryonic chick hearts are used, the upstroke velocity is much lower in single cells, in small clusters of cells, and in sparse monolayers (17,49,51,95) than...

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Section: Effect Of Ba 2ϩ On Spontaneous Activitymentioning

confidence: 92%

Section: Effect Of Almokalant On Spontaneous Activitymentioning

confidence: 99%

Section: Spontaneous Activity: Cell-to-cell Variability and Activity-mentioning

confidence: 99%

Section: Cell Isolationmentioning

confidence: 99%

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