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Angiotensin II activation of a chloride current in rabbit cardiac myocytes.
Author(s) -
Morita H,
Kimura J,
Endoh M
Publication year - 1995
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1995.sp020572
Subject(s) - rabbit (cipher) , angiotensin ii , myocyte , current (fluid) , chemistry , medicine , chloride , renin–angiotensin system , biophysics , cardiology , endocrinology , biology , blood pressure , physics , computer science , computer security , organic chemistry , thermodynamics
1. The effects of angiotensin II (Ang II) on membrane currents were investigated in single ventricular myocytes from the rabbit heart by the whole‐cell voltage‐clamp method. 2. In the presence of an inhibitor of Ca2+ currents (nifedipine at 3 microM or CdCl2 at 0.3 mM) and a beta‐adrenoceptor blocker (bupranolol at 1 microM), 1 microM Ang II significantly increased the membrane conductance. 3. After elimination of K+ from external and internal solutions and its replacement by Cs+, Ang II at 0.1 microM increased an outwardly rectifying current that reached a maximum after about 40 min. The effect was concentration dependent (10(‐9)‐10(‐6) M) and was inhibited by saralasin, an antagonist of Ang II receptors. 4. The reversal potential of the Ang II‐induced current in the absence of K+ was compatible with the Cl‐ equilibrium potential at various external concentrations of Cl‐. 5. A Cl‐ channel blocker, 4,4'‐dinitrostilbene‐2,2'‐disulphonic acid (DNDS, at 5 mM), reversibly decreased the Ang II‐induced current. 6. The Ang II‐induced current developed when the internal solution contained Ca2+ (pCa 7.2 or 7.0) but not when it contained 10 mM EGTA without Ca2+. 7. Besides developing a Cl‐ current, Ang II at 1 microM increased the inwardly rectifying K+ current (IK1) and this effect reached maximum within 3 min. 8. The effect of Ang II on the action potential was biphasic: the duration of the action potential was initially reduced and then it was increased. 9. These results suggest that Ang II induces a Cl‐ current that appears likely to modulate the action potential in rabbit ventricular myocytes.