Modulation of calcium channel currents in guinea-pig single ventricular heart cells by the dihydropyridine Bay K 8644.

摘要: 1. A single glass micropipette voltage clamp technique with intracellular dialysis was used to study Ba2+ currents in isolated ventricular cells from guinea-pig hearts. Effects of the 1,4-dihydropyridine Bay K 8644 on whole-cell were evaluated at 37 degrees C. 2. increased peak test potentials between -50 and +20 mV shifted current-voltage relationships towards hyperpolarizing (leftward shift for Ca2+ channel activation, 13.8 +/- 4.1 mV; n = 9; 8644, 5 mumol/l). 3. The times diminished over range tested -40 after parallel a shortening time constant activation that estimated fits recorded d2f model. 4. decay fitted two exponentials including pedestal. compound accelerated fast whole range. amplitude rapidly inactivated component strikingly application 8644. 5. steady-state inactivation using 0.5 or s pre-pulse 10.3 5.2 4; 6. change course 8644-modified cannot be described solely by decrease backward rate coefficient an open closed state (Sanguinetti, Krafte & Kass, 1986). effects can both qualitatively quantitatively model current-dependent (Standen Stanfield, 1982), assuming lower affinity internal binding site than Ca2+.