[Effects of medullary pyramidal stimulation on myocardial contractility in anesthetized dogs].
In anaesthetized dogs, medullary pyramid stimulation produces a decrease of myocardial contractility. The peak of the first derivative of the left ventricular pressure (dP/dt max) was used to assess myocardial contractility; this index is independent of afterload. Medullary pyramid stimulation produces a decrease of dP/dt max and of the maximal left ventricular pressure (L.V.P. max) also, after bilateral vagotomy. But the same stimulation induces only a decrease of L.V.P. max after inhibiting beta-adrenergic efferences and bilateral vagotomy. Just as corticopyramidal fibres inhibiting alpha-adrenergic vascular tone, one does consider the existence of corticopyramidal fibres inhibiting beta-adrenergic efferences to myocardium.
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D006321:Heart / Q000502:physiology; D008526:Medulla Oblongata / Q000502:physiology*; D009200:Myocardial Contraction; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology
Effets de la stimulation des pyramides bulbaires sur la contractilité myocardique chez le chien narcosé.