[Effect of stimulation of the hypothalamic paraventricular nucleus on the electrical and contractile characteristics of the myocardium in dogs].
Electrical stimulation of the hypothalamic paraventricular nucleus results in bradycardia and hypotension. A direct transtemporal approach was used to implant an insulated electrode in the site of the third ventricle. The bradycardia and hypotension have been studied previously and have been shown to be due to inhibition of the alpha and beta vascular and myocardiac adrenergic receptors. The effects of this inhibition on the electrical appearances and the mechanical and phonocardiographic parameters of myocardial contractility were observed in this present study. The force and velocity of LV isometric contraction were reduced as shown by reduction in dP/dT, the delay in its peak and the reduction of the angle between the upstroke of ventricular contraction with the base line. The onset of left ventricular ejection was delayed. The high frequency (60 and 140 Hz) components of the first heart sound disappeared, confirming their contribution to the intensity of this sound. The ECG rapid QRS phase and AV conduction time were unchanged, but the slow phase of the T wave became more negative as the depressant effect on the myocardium increased.
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D004562:Electrocardiography; D006321:Heart / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology*; D009200:Myocardial Contraction; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D010701:Phonocardiography; D016276:Ventricular Function
Influence de l'excitation du noyau paraventriculaire hypothalamique sur les caractéristiques électriques et contractiles du myocarde chez le chien.