[2-component contraction of mammalian myocardium due to noradrenaline].
The effect of noradrenaline (2 mg/l) on contractile response, its first derivative, and transmembrane action potential of isolated papillary muscles of guinea pigs, was studied. The muscles were continuously superfused with normal Tyrode's solution at 20-22 degrees C and stimulated at 0.3 Hz. Under the effect of noradrenaline the contraction consisted of two components which became more obvious at low-frequency stimulation or in the first contraction after a long resting period, the second component's amplitude being increased, at that. The increase corresponded to prolongation of the AP. In presence of noradrenaline the Bowditch's staircase became positive.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology*; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology; D010812:Physical Stimulation
D009638:Norepinephrine
Dvukhkomponentnoe sokrashchenie miokarda mlekopitaiushchego pri deĭstvii noradrenalina.