ISSN:
1432-2013
Keywords:
Vascular Smooth Muscle
;
Mechanisms of Activation
;
Noradrenaline
;
Potassium-Induced Depolarization
;
Calcium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. Contraction of helical strips of the rat aorta was induced by 3 μg/ml of noradrenaline or by potassium-rich solution (80–120 mM K). The resulting amplitudes of contraction were maximal for these respective ways of activation and showed almost the same value in this preparation. 2. The noradrenaline-induced tension, but not the contraction induced by depolarization, decreased, when the hydrogen ion concentration of the bath solution was increased. Furthermore, the response to noradrenaline was more sensitive to a blockade of the adrenergic alpha-receptors or a variation of the bath temperature. 3. Since, after the application of papaverine, the amplitudes of contraction produced by noradrenaline or depolarization were diminished to the same degree, papaverine probably acts on the later steps of the activation-contraction mechanism. 4. When verapamil (iproveratril) was applied in order to inhibit excitationcontraction coupling, tension development after depolarization was influenced to a higher degree than noradrenaline-induced contraction. 5. The fact that it is possible to inhibit the response to depolarization without substantial influence on the response to noradrenaline andvice versa led to the conclusion that in the rat aorta depolarization on the one hand and noradrenaline on the other hand act via different mechanisms of activation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00588736
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