ISSN:
1432-2013
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The effect of adrenaline on the relation between the maximum rate of rise of the action potential and the membrane potential (varied by applying current) was studied on excised Purkinje fibers and strips of the right atrium of dog's heart. This relation was not changed either in Tyrode's solution with normal or 3 to 5 times increased potassium and/or 10 times reduced calcium concentration. The slight increase of the resting potential by adrenaline accounted for the increase of the overhoot of the action potential. The increase of the resting potential caused by adrenaline also occurred when the preparation was poisoned by 2,4-dinitrophenol (0.2 m Mol) or NaCN (5 mMol), or when the Tyrode's solution was saturated by N2. When, however, a spontaneously beating dog sinus preparation was treated with iodoacetic acid (2 mMol) for more than 50 min. adrenaline showed no effect on the maximum diastolic potential and the frequency of the pacemaker. Replacing sodium by lithium in the Tyrode's solution abolished automaticity in the sinus preparation. In this solution adrenaline failed to induce spontaneous activity and had no effect on the resting potential. It is concluded that adrenaline does not affect sodium permeability but activates active cation transport.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00362377
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