Increased cardiac sympathetic nerve activity following acute myocardial infarction in a sheep model

摘要: The time course of cardiac sympathetic nerve activity (CSNA) following acute myocardial infarction (MI) is unknown. We therefore undertook serial direct recordings CSNA, arterial blood pressure (MAP) and heart rate (HR) in 11 conscious sheep before after MI, compared them with 10 controls. Conscious CSNA were taken daily from electrodes glued into the thoracic nerves. Infarction was induced under pethidine diazepam analgesia by applying tension to a coronary suture. MI size assessed left ventricular planimetry (%) at postmortem, peak troponin T brain natriuretic peptide levels (BNP). Baroreflex slopes using phenylephrine-nitroprusside ramps. mean infarcted area 14.4 ± 2.9%, 1.88 0.39 μg l−1 BNP 8.4 1.3 pmol l−1. There no differences haemodynamic parameters or between groups baseline. MAP HR remained constant MI. burst frequency increased baseline 55.8 7.1 bursts min−1 77.5 8.7 2 h post-MI, elevated for days (P < 0.001). also sustained 7 (P= 0.016). pulse interval did not change. increases within 1 onset least days. duration this response may be longer because recording fields decrease time. This result consistent excitatory reflex.