Abstract
The temperature dependence of cardiac active Na transport is studied in voltage clamped sheep Purkinje fibres by means of simultaneous measurements of the membrane current (I) and the intracellular Na activity (a iNa ). During activation of the Na pump a transient outward current (ΔI) anda iNa decline exponentially with an identical time constant (τ). The transient outward current and the decline ina iNa are blocked by 10−4 M dihydroouabain (DHO). Lowering the temperature from 42°C to 17°C prolongs τ. The electrogenic fraction (e.f.) of the active Na efflux remains unaffected. The Q10 value of the active Na transport derived from the changes of τ varies within the temperature range studied. The Q10 amounts to ∼1.2 between 42°C and 35°C, to ∼2.4 between 35°C and 22°C and to ∼2.1 between 35°C and 17°C. Correspondingly the activation energy of the active Na transport is not constant between 42°C and 17°C. It is calculated to be 3.4 kcal/mol between 42°C and 35°C, 15.9 kcal/mol between 35°C and 22°C and 12.4 kcal/mol between 35°C and 17°C. Variations in temperature change the maximal rate constant of the active Na transport, whereas the sensitivity of the Na pump towards the extracellular K concentration (Ko) is little affected. The unidirectional active Na efflux of a fibre as a function of the intracellular Na concentration (Nai) at 35°C and 22°C is derived from the experemental data. The relationship is linear over the narrow Nai range studied but seems to be more complex when a wider Nai range is considered.
Similar content being viewed by others
References
Aronson RS, Gelles JM, Hoffmann BF (1973) A new method for producing short cardiac Purkinje fibres suitable for voltage clamp. J Appl Physiol 34:527–530
Bosteels S, Carmeliet E (1967) Na efflux in cardiac Purkinje fibres: effect of extracellular K, temperature, Na N3 and ouabain. Arch Int Physiol Biochim 75:345–346
Deck KA, Kern R, Trautwein W (1964) Voltage clamp technique in mammalian cardiac fibers. Pflügers Arch 280:50–62
Deitmer JW, Ellis D (1978) The intracellular sodium activity of cardiac Purkinje fibres during inhibition and re-activation of the Na−K pump. J Physiol (Lond) 284:241–259
Den Hertog A, Ritchie JM (1969) A comparison of the effect of temperature, metabolic inhibitors and of ouabain on the electrogenic component of the sodium pump in mammalian nonmyelinated nerve fibres. J Physiol (Lond) 204:523–538
Eisner DA, Lederer WJ (1980) Characterization of the electrogenic sodium pump in cardiac Purkinje fibres. J Physiol (Lond) 303:441–474
Eisner DA, Lederer WJ, Vaughan-Jones RD (1981a) The dependence of sodium pumping and tension on intracellular sodium activity in voltage-clamped sheep Purkinje fibres. J Physiol (Lond) 317:163–187
Eisner DA, Lederer WJ, Vaughan-Jones RD (1981b) The effects of rubidium ions and membrane potential on the intracellular sodium activity of sheep Purkinje fibres. J Physiol (Lond) 317:189–205
Ellis D (1977) The effects of external cations and ouabain on the intracellular sodium activity of sheep heart Purkinje fibres. J Physiol (Lond) 273:211–240
Gadsby DC (1980) Activation of electrogenic Na+/K+ exchange by extracellular K+ in canine cardiac Purkinje fibers. Proc Natl Acad Sci USA 77:4035–4039
Gadsby DC, Cranefield PF (1979) Direct measurement of changes in sodium pump current in canine cardiac Purkinje fibers. Proc Natl Acad Sci USA 76:1783–1787
Glitsch HG (1982) Electrogenic Na pumping in the heart. Ann Rev Physiol 44:389–400
Glitsch HG, Pusch H (1984) On the temperature dependence of active Na transport in sheep Purkinje fibres. Pflügers Arch 400 (Suppl):R 5
Glitsch HG, Pusch H, Venetz K (1976) Effects of Na and K ions on the active Na transport in guinea-pig auricles. Pflügers Arch 365:29–36
Glitsch HG, Pusch H, Schumacher Th, Verdonck F (1982) An identification of the K activated Na pump current in sheep Purkinje fibres. Pflügers Arch 394:256–263
Glitsch HG, Pusch H, Schumacher T (1984a) Temperature dependence of the cardiac Na K pump as studied by Na sensitive microelectrodes. In: Kessler M, Harrison D, Höper J (eds) Recent advances in the theory and application of ion-sensitive electrodes in physiology and medicine. Springer, Berlin Heidelberg New York (in press)
Glitsch HG, Pusch H, Schumacher T (1984b) Dihydroouabain-sensitive Na efflux at low intracellular Na activity in sheep Purkinje fibres. Pflügers Arch 400 (Suppl): R 5
Hodgkin AL, Keynes RD (1955) Active transport of cations in giant axons fromSepia andLoligo. J Physiol (Lond) 128:28–60
Höfer M (1977) Transport durch biologische Membranen. Verlag Chemie, Weinheim New York, pp 1–128
Hororicz P, Taylor JW, Waggoner DM (1970) Fractionation of sodium efflux in frog satorius muscles by strophanthidin and removal of external sodium. J Gen Physiol 55:401–425
Isenberg G, Trautwein W (1975) Temperature sensitivity of outward current in cardiac Purkinje fibers. Evidence for electrogenicity of active transport. Pflügers Arch 358:225–234
Langer GA (1968) Ion fluxes in cardiac excitation and contraction and their relation to myocardial contractility. Physiol Rev 48:708–757
Mobley BA, Page E (1972) The surface area of sheep cardiac Purkinje fibres. J Physiol (Lond) 220:547–563
Schuurmans Stekhoven F, Bonting SL (1981) Transport adenosine triphosphatases: properties and functions. Physiol Rev 61:1–76
Schwartz A, Lindenmayer GE, Allen JC (1975) The sodium-potassium adenosine triphosphatase: pharmacological, physiological and biochemical aspects. Pharmacol Rev 27:3–134
Sperelakis N, Lee EC (1971) Characterization of (Na+, K+)-ATPase isolated from embryonic chick hearts and cultured chick heart cells. Biochim Biophys Acta 233:562–579
Author information
Authors and Affiliations
Additional information
Supported by the Deutsche Forschungsgemeinschaft (SFB 114 “Bionach”)
Rights and permissions
About this article
Cite this article
Glitsch, H.G., Pusch, H. On the temperature dependence of the Na pump in sheep Purkinje fibres. Pflugers Arch. 402, 109–115 (1984). https://doi.org/10.1007/BF00584839
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00584839