A long lasting Ca2+-activated outward current in guinea-pig atrial myocytes.

Pflügers Archiv : European journal of physiology
I Baró, D Escande

Abstract

Among other characteristics, the steady-state current-voltage relationship of patch-clamped single atrial myocytes from guinea-pig hearts is defined by an outward current hump in the potential region -15 to +40 mV. This hump was reversibly suppressed by Co2+ (3 mM) or nitrendipine (5 microM) and enhanced by Bay K 8644 (5 microM). The maintained outward current component suppressed by Co2+ extended between -15.2 +/- 1.9 mV and +39.5 +/- 1.7 mV (mean +/- SEM of 14 cells) and has an amplitude of 95.7 +/- 9.4 pA at +10 mV. In isochronal I-V curves, the hump was already visible at 400 ms with essentially the same amplitude as at 1500 ms. The Co2+-sensitive outward current underlying the hump was poorly time-dependent during 1.5 s voltage pulses but slowly relaxed upon repolarization. Tail currents reversed near the K+ equilibrium potential under our experimental conditions. The current hump of the steady-state I-V curve was also abolished by caffeine (10 mM) or ryanodine (3 microM), both drugs that interfere with sarcoplasmic reticulum function. Apamin (1 microM) or quinine (100 microM) but not TEA (5-50 mM) markedly reduced its amplitude. However, at similar concentrations as required to inhibit the hump, both apamin and quinine ap...Continue Reading

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Citations

Apr 1, 1991·Pflügers Archiv : European journal of physiology·K BenndorfH Hirche
Jul 31, 1990·Neuroscience Letters·R L Parsons, L M Konopka
Aug 1, 1992·Pflügers Archiv : European journal of physiology·A P BraunW R Giles
Jan 1, 1991·Critical Reviews in Biochemistry and Molecular Biology·A K BejR M Atlas
Oct 15, 2019·Frontiers in Physiology·Laura Martinez-MateuAdemuyiwa S Aromolaran
Jan 1, 1992·The American Journal of Physiology·C H FollmerT J Colatsky

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