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To determine the effects of HOE 694, a new and potent Na＋- H＋ exchanger blocker, on transient inward current (Iti) and Na＋- Ca2＋ exchange during hypoxia- reoxygenation in guinea pig cardiomyocytes. Methods. Cardiomyocytes were isolated from adult guinea pig ventricle. Experiment was performed in an experimental chamber that allowed the cells to be exposed to a sufficiently low O2 pressure. The cells were subjected to hypoxia and reoxygenation. The ionic currents were studied with patch clamp technique. Results. In the absence of HOE 694, hypoxia- reoxygenation induced Iti in 12 of 15 experiments; but in cardiomyocytes pretreated with HOE 694 (10～ 50μ mol/L), the incidence of Iti observed during reoxygenation was reduced to 5 of 11 experiments and 3 of 10 experiments, P Conclusions. Blockade of the Na＋- H＋ exchange by HOE 694 could reduce Ca2＋ overload upon hypoxia- reoxygenation, and inhibition of Na＋- H＋ exchange may also indirectly decrease Na＋- Ca2＋ exchange activity during hypoxia.
To determine the effects of HOE 694, a new and potent Na + - H + exchanger blocker, on transient inward current (Iti) and Na + - Ca2 + exchange during hypoxia- reoxygenation in guinea pig cardiomyocytes. Methods. Cardiomyocytes were isolated from adult guinea pig ventricle. The experiment was performed in an experimental chamber that allowed the cells to be exposed to a sufficient low O2 pressure. The cells were subjected to hypoxia and reoxygenation. The ionic currents were studied with patch clamp technique. In the absence of HOE 694, hypoxia - reoxygenation induced Iti in 12 of 15 experiments; but in cardiomyocytes pretreated with HOE 694 (10-50 μ mol / L), the incidence of Iti observed during reoxygenation was reduced to 5 experiments and 3 of 10 experiments, P Conclusions. Blockade of the Na + - H + exchange by HOE 694 could reduce Ca2 + overload upon hypoxia-reoxygenation, and inhibition of Na + - H + exchange may also be affected decrease Na + - Ca2 + exchange activity during hypoxia.