Sinus node extracellular potassium transients following vagal stimulation

Kronhaus, Kenneth D.; Spear, Joseph F.; Moore, E. Neil; Kline, Richard

doi:10.1038/275322a0

Cited by 13 publications

(7 citation statements)

References 15 publications

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“…2 and 3). This finding is similar to that in canine Purkinje fibres (Kline & Kupersmith, 1982) and rabbit sinus node (Kronhaus et al 1978). Also, we noted a small additional increase in [K+].…”

Section: Discussionsupporting

confidence: 90%

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Triggered activity in atrial fibres of canine coronary sinus: role of extracellular potassium accumulation and depletion.

Henning

Kline

Siegal

et al. 1987

The Journal of Physiology

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1. Bursts of triggered activity can be induced in atrial fibres of the canine coronary sinus exposed to catecholamines. During a triggered burst there is an initial acceleration of rate accompanied by depolarization of the maximum diastolic potential (m.d.p.) followed by slowing of the rate and termination accompanied by hyperpolarization. 2. We have used extracellular K+-sensitive micro-electrodes (potassium ISE) to monitor extracellular K+ concentration ([K+]o) during and following triggered activity, while simultaneously measuring membrane potential with conventional intracellular micro-electrodes. 3. We found that the initial increase in rate during triggered activity is accompanied by increased [K+]o and depolarization. Later rate slowing and m.d.p. hyperpolarization is accompanied by decline of extracellular K+ accumulation. Following termination of triggered activity, extracellular K+ depletion occurred. 4. The decline of [K+]o and slowing of rate are known responses to enhanced Na+-K+ pump activation, as is the post-triggering depletion of extracellular K+. 5. Strophanthidin, which blocks the Na+-K+ pump, also blocks the [K+]o decline, the slowing of rate seen towards the end of the triggered episode, and the post-triggering depletion of extracellular K+. 6. Separate experiments studying the effects of elevated bath K+ and depolarizing current on triggering rate and delayed after-depolarization amplitude support our hypothesis that the rate profile of the triggered episode is to a large extent controlled by variations in m.d.p. subsequent to extracellular K+ accumulation and Na+-K+ pump activation.

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Section: Discussionsupporting

confidence: 90%

“…1 Kline & Kupersmith, 1982). (Kline & Morad, 1978;Kronhaus et al 1978;Kline & Kupersmith, 1982). More importantly they indicated one further observation, that there is an additional extracellular K+ accumulation during the delayed after-depolarization.…”

Section: Extracellular K+ Accumulation In Coronary Sinus Tissue Durinmentioning

confidence: 87%

Triggered activity in atrial fibres of canine coronary sinus: role of extracellular potassium accumulation and depletion.

Henning

Kline

Siegal

et al. 1987

The Journal of Physiology

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“…This is in contrast to previous in vitro results on mammalian cardiac tissue (7,12,13,16). The decline during prolonged stimulation as well as the [K ϩ ] o depletion that followed cessation of stimulation have previously been ascribed to Na-K-ATPase-mediated active processes redistributing K ϩ from the extracellular space (7,12,15). The reasons for the discrepancy in the time course of rate-related changes in [K ϩ ] o between our measurements and those obtained in isolated mammalian cardiac muscle are unclear, but include differences in the experimental conditions [e.g., presence of adrenaline (7)], regulation of Na-K-ATPase by the intracellular levels of Na ϩ and ATP (21,33).…”

Section: Previous Studiescontrasting

confidence: 54%

“…Because fluctuations in [K ϩ ] o activity within this range have been shown to influence cardiac electrophysiological properties by altering K ϩ equilibrium potential and K ϩ conductance (1,3,4,11,(13)(14)(15)28), rate-dependent changes in K ϩ distribution must be considered when studying the pattern of electrical activation and inactivation in the atrium. Because the magnitude and time course of K ϩ accumulation critically depend on the diffusion distance between the cells and the capillary blood (or in the case of isolated superfused preparations the bathing solution), the shorter distances between the cells and the capillaries in the intact heart, as opposed to the superfused tissue, would be expected to reduce the extent of [K ϩ ] o accumulation.…”

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confidence: 99%

Rate-dependent [K⁺]_o accumulation in canine right atria in vivo: electrophysiological consequences

Miyata

Dowell

Zipes

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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ms] to 0.80 Ϯ 0.09 mM (CL ϭ 250 ms) above baseline (3.50 Ϯ 0.08 mM at CL ϭ 380 ms; n ϭ 5). During rapid pacing-induced atrial fibrillation, peak increase in [K ϩ ]o averaged 0.80 Ϯ 0.07 mM (n ϭ 5). Whole cell current-clamp measurements in single right atrial myocytes (n ϭ 5) showed that raising [K ϩ ]o from 3 to 5 mM in 1-mM steps progressively depolarized resting membrane potential and reduced both phase 0 action potential amplitude and maximal upstroke velocity. Multisite epicardial mapping (n ϭ 4) demonstrated that sudden rate increases changed longitudinal conduction velocity (CVL) by Ϫ3.6 Ϯ 1.8% to Ϫ5.9 Ϯ 1.2% over a CL range of 330 to 250 ms. Our observations suggest that rate-related [K ϩ ]o accumulation in vivo is of sufficient magnitude to modulate those cellular electrophysiological properties that determine atrial CVL.

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“…Adjustments could be made to compensate for the slower response time of the ion-sensitive barrel by slowing the response time of the faster reference barrel with a variable active filter while at the same time enhancing the response time of the slower ion-sensitive barrel with capacitive compensation (Kronhaus, Spear, Kline & Moore, 1978). It should be noted that both barrels detect potential, but superimposed on the ion-sensitive barrel output is an additional electrical potential which reflects the changes in local K+ activity at the electrode tip.…”

Section: Methodsmentioning

confidence: 99%

Effects of extracellular potassium accumulation and sodium pump activation on automatic canine Purkinje fibres

Kline

Kupersmith

1982

The Journal of Physiology

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SUMMARY1. Double barrel potassium-sensitive micro-electrodes were used to measure fluctuations in extracellular potassium ion concentration in large automatic canine Purkinje fibres.2. Slow accumulations of potassium were seen in the extracellular space during prolonged beating. Following cessation of prolonged beating, a depletion of extracellular potassium ions was noted.3. The time course of these slow changes in extracellular potassium concentration were shown to be a function of the diffusion properties of the preparation, and the rate and degree of activation of the sodium pump.4. Action potential duration and maximum diastolic potential were simultaneously monitored during and after these periods of rapid stimulation, using conventional intracellular micro-electrodes.5. Initial depolarization and later hyperpolarization of the maximum diastolic potential appeared to occur as a direct result of changes in extracellular potassium concentration and level of pump activation induced by the sudden and prolonged alteration in stimulus rate.6. Following prolonged stimulation, dramatic changes in the automatic beating rate were correlated with changes in extracellular potassium and pump rate, and their effects on the maximum diastolic potential and other parameters of the diastolic potential depolarization.7. For some locations of the potassium-sensitive electrode tip, large fluctuations in extracellular potassium were seen during single beats. Alterations in action potential duration during abrupt rate changes appear to derive in part from modulation by these extracellular potassium concentration fluctuations altering net membrane currents. Slower shifts in action potential duration appear correlated to the degree of sodium pump activation.

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Sinus node extracellular potassium transients following vagal stimulation

Cited by 13 publications

References 15 publications

Triggered activity in atrial fibres of canine coronary sinus: role of extracellular potassium accumulation and depletion.

Triggered activity in atrial fibres of canine coronary sinus: role of extracellular potassium accumulation and depletion.

Rate-dependent [K⁺]_o accumulation in canine right atria in vivo: electrophysiological consequences

Effects of extracellular potassium accumulation and sodium pump activation on automatic canine Purkinje fibres

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Sinus node extracellular potassium transients following vagal stimulation

Cited by 13 publications

References 15 publications

Triggered activity in atrial fibres of canine coronary sinus: role of extracellular potassium accumulation and depletion.

Triggered activity in atrial fibres of canine coronary sinus: role of extracellular potassium accumulation and depletion.

Rate-dependent [K+]o accumulation in canine right atria in vivo: electrophysiological consequences

Effects of extracellular potassium accumulation and sodium pump activation on automatic canine Purkinje fibres

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Rate-dependent [K⁺]_o accumulation in canine right atria in vivo: electrophysiological consequences