title: Suppression of the cardiac performance during recovery after strenuous sympathetic nerve activity.
abstract: To examine whether myocardial contractility is suppressed during recovery from strenuous sympathetic nerve activity, the cardiac sympathetic nerve was stimulated for 1 min at 20 Hz in open-chest anesthetized dogs (n = 6). Myocardial contractility was compared between stimulation at 20 Hz (strenuous) and stimulation at 2 Hz (physiological range). Inotropic activity was assessed as the maximal value of the first derivative of left ventricular pressure. The inotropic activity was significantly below the prestimulation control level at 5 min after the end of the strenuous stimulation (68+/-7% of the control value; p < 0.05). The inotropic activity then increased toward the prestimulation level. In contrast, the inotropic activity with 2-Hz stimulation decreased toward the prestimulation level but never fell below that level during recovery. In another experiment (n = 10), 50% glucose solution was injected 5 min after the end of the strenuous stimulation (20 Hz), i.e. when the inotropic activity reached the nadir. The inotropic activity increased significantly (p < 0.01) above the prestimulation level between 7 and 20 min after stimulation. Maximal response (121+/-7% of the control value) was observed at approximately 10 min. These results suggest that transient myocardial suppression occurs after strenuous sympathetic nerve activity and that high-energy phosphate is substantially consumed during strenuous sympathetic activity, resulting eventually in myocardial suppression.
authors.affiliation: Department of Medicine, Tashirodai Hospital, Yamaguchi, Japan. yuknrepi@orange.ocn.ne.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Masuda
mesh_terms: D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004285:Dogs; D004558:Electric Stimulation / Q000379:methods; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology; D007262:Infusions, Intravenous; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology
chemical_list: D005947:Glucose