The effect of cardiac glycosides on the Na+ pump current‐voltage relationship of isolated rat and guinea‐pig heart cells.

Hermans, A N; Glitsch, H. G.; Verdonck, Fons

doi:10.1113/jphysiol.1994.sp020438

Cited by 15 publications

(12 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given a cell surface area of about 1000 /um2, the estimated current density would range from 0-13 to 0'6 1/A cm-2, a density similar to values estimated in other cells (e.g. Sejersted, Wasserstrom & Fozzard, 1988;Hermans, Glitsch & Verdonck, 1994;Glitsch & Tappe, 1995). The reversal potential of the sodium pump current was more negative than the resting membrane potential.…”

Section: Discussionsupporting

confidence: 52%

“…This experimental condition is commonly used to study the sodium pump current (e.g. Bielen et al 1991;Hermans et al 1994Hermans et al , 1995. However, the free energy of ATP hydrolysis (AGATP ) and the reversal potential of Ip would have been artificially maintained at very negative values, thus maximizing the effect of I,.…”

Section: Discussionmentioning

confidence: 99%

“…Sejersted, Wasserstrom & Fozzard, 1988;Hermans, Glitsch & Verdonck, 1994;Glitsch & Tappe, 1995). The reversal potential of the sodium pump current was more negative than the resting membrane potential.…”

Section: Inward Rectificationmentioning

confidence: 92%

“…This experimental condition is commonly used to study the sodium pump current (e.g. Bielen et al 1991;Hermans et al 1994Hermans et al , 1995 (Glitsch & Tappe, 1995). In the ionic conditions of the present study one can calculate that AGATP would be about -50 kJ mol-with 5 mM ATP, 1 mM ADP and 1 mM Pi, and Erev would theoretically reach -280 mV.…”

Section: Inward Rectificationmentioning

confidence: 93%

See 3 more Smart Citations

Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Trotier

Døving

1996

The Journal of Physiology

View full text Add to dashboard Cite

Whole-cell measurements were made from microvillous receptor neurones isolated from the frog vomeronasal organ. We examined the mechanisms that determined the value of the resting membrane potential. The resting membrane potential of neurones is generally and K+ ions across the cell membrane and is responsible for thought to be set by a passive diffusion of K+ ions through the maintenance of the high internal potassium non-voltage-gated channels which are open at rest. In concentration and the low internal sodium concentration. previous studies of frog vomeronasal receptor cells (Trotier, Since the transport process is electrogenic, because three

show abstract

Section: Discussionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Section: Inward Rectificationmentioning

confidence: 92%

Section: Inward Rectificationmentioning

confidence: 93%

See 2 more Smart Citations

Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Trotier

Døving

1996

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…(Strophanthidin increased conductance by 0.44 ± 0.40 nS, n = 8.) Pump currents in other tissues are also associated with little change in conductance (Gadsby & Nakao, 1989; Hermans et al 1994). Figure 2 also shows very little hyperpolarization‐activated inward current ( I h ) compared with that which is normally recorded in dopamine neurons.…”

Section: Resultsmentioning

confidence: 99%

Sodium pump evokes high density pump currents in rat midbrain dopamine neurons

Shen¹,

Johnson²

1998

The Journal of Physiology

View full text Add to dashboard Cite

Patch pipettes contained various concentrations of Na+ ([Na+]pip) in order to record strophanthidin‐sensitive currents under voltage clamp in dopamine neurons in slices of rat substantia nigra and ventral tegmental area. When [Na+]pip was 40 mm and the external K+ concentration ([K+]o) was 2.5 mm, strophanthidin (10 μm) evoked 461 ± 121 pA of inward current. This effect was concentration dependent, with an EC50 of 7.1 ± 2.6 μm. At potentials of −60 to −120 mV, strophanthidin‐induced currents were not associated with significant changes in chord conductance. Strophanthidin (10 μm) evoked 234 ± 43 pA of inward current when [Na+]pip was 0.6 mm, and 513 ± 77 pA when [Na+]pip was 80 mm. Despite higher pump currents with greater [Na+]pip, the strophanthidin EC50 was not significantly different for any of six different [Na+]pip. Sodium pump currents were half‐maximal when the [Na+]pip was about 1.3 mm. Maximum pump current was estimated at 830 pA (29 μA cm−2) at concentrations of intracellular Na+ that were assumed to be saturating (50–100 mm). Strophanthidin currents were smaller in a reduced [K+]o (EC50= 0.2 mm). These data show that intracellular Na+ loading evokes relatively large pump currents. Our results are consistent with the physiological role of the sodium pump in burst firing in midbrain dopamine neurons

show abstract

Cardiac Na+ pump current-voltage relationships at various transmembrane gradients of the pumped cations

Glitsch

Schwarz

Tappe

1996

Biochimica et Biophysica Acta (BBA) - Biomembranes

View full text Add to dashboard Cite

Thermodynamic considerations predict changes of the Na+ pump current (Ip)-voltage (V) relationship of animal cells upon variations of the electrochemical gradients against which cations must be pumped. Experimental data in support of the predictions are sparse. Therefore, the effect on the Ip-V relationship of various electrochemical gradients for pumped Na+ and Cs+ was studied at constant deltaGATP (approximately -39kJ/mol in cardioballs from sheep Purkinje fibres. Control of the subsarcolemmal ionic concentrations during whole-cell recording was ensured by activation of Ip below its half maximal activity or by measuring the initial Ip following reactivation of the Na+/K+ pump. With gradients close to physiological conditions Ip was outward over the entire voltage range and the Ip-V relationship showed a maximum near zero potential. Steepening the ionic gradients diminished the Ip amplitude and outward pump current was no longer detectable between -65 mV and -110 mV. Flattened ionic gradients increased the Ip amplitude and shifted apparently the reversal potential Erev to more negative values. These changes are in line with theoretical considerations. The measured Ip-V relationships were fitted by curves computed on the basis of a simplified Post-Albers scheme of Na+/Cs+ pumping. The increased Ip amplitude at flat ionic gradients was due to a decrease of [Cs+]o for half maximal Ip activation. The maximal Ip amplitude remained unaffected

show abstract

The effect of cardiac glycosides on the Na+ pump current‐voltage relationship of isolated rat and guinea‐pig heart cells.

Abstract: 1. Whole-cell recording from isolated rat and guinea-pig ventricular myocytes revealed a change of the cardiac Na+ pump current (1p)-voltage (V)

Cited by 15 publications

References 13 publications

Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Direct influence of the sodium pump on the membrane potential of vomeronasal chemoreceptor neurones in frog.

Sodium pump evokes high density pump currents in rat midbrain dopamine neurons

Cardiac Na+ pump current-voltage relationships at various transmembrane gradients of the pumped cations

Contact Info

Product

Resources

About