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KMID : 0376219700070020117
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Chonnam Medical Journal
1970 Volume.7 No. 2 p.117 ~ p.128
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The Negative Chronotropic Responses of the Isolated Rabbit Atria to Sympathomimetic Amines
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Abstract
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1) The chronoitropic responses to cumulative doses (10-7, 10-6, 10-5, 10-4g/ml) of sympathomimetic amines (nirepinephrine, epinephrine, isoproterenol, pheuyhepbrine)were investigated in the isolated rabbit atrial preparations.
2) When the atrial late was -increased, by the first dose (10-7g/m1) of the amines, the additional doses (above :10-6g/ml) produced no further significant rate increase. On the contrary NE and EP (10-4g/ml) produce] significant rate decrease.
3) When the atria were exposed to ISP (10-4g/ml); NE, EP and PE produced rate decrease. When the atria were,, exposed to NE ´(10-5g/ml), EP and PE produced rate change or decrease of the rate and ISP produced less increasing effect.
4) Pronethalol and propranolol inhibited the rate increase induced by the small dose (l0-7g/ml) of the amines. These agents, however, potentiated the rate increasing effect of the larger doses of NE, ISP and EP.
5) Ergotamine inhibited the rate increase by the small doses (10-7g/ml) of the amines.
6) Pronethalol did not inhibit, but ergotamine did inhibit the negative chronotropic effect of NE and EP, which was observed when the atria were exposed to JSP or NE.
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