Abstract
The report of bradycardia caused by propofol is increasing. In the experiment, we investigated the chronotropic function of propofol and the underlying mechanism. Rabbits of both sexes were randomly divided into 4 groups: propofol 5 mg/kg group, 10 mg/kg group, 15 mg/kg group, and sham group. Heart rate and frequency of vagal efferent discharge were recorded before the injection and 0, 0.5, 1, 2, and 10 min after the injection through intravenous mode. Then, their hearts were removed, and sinoatrial nodes were dissected. The action potentials of the sinus node pacemaker cells were recorded by the intracellular glass microelectrode technique, and the sinoatrial (SA) node was exposed to propofol 1, 3, 5, and 10 µM respectively. The action potentials were recorded after the sinoatrial nodes were exposed to each concentration of propofol for 15 min. Our results show that the heart rate significantly decreased, and the vagal efferent discharge was significantly increased at 0, 0.5, 1, and 2 min after the injection, respectively. Besides, as the dose increases, the magnitude of change shows a dose-dependent manner. Propofol exerts a negative chronotropic action on sinoatrial node pacemaker cells. The drug significantly decreased APA, VDD, RPF, and prolonged APD90 in a concentration-dependent manner. These effects may be the main mechanism of propofol-induced bradycardia in clinical study.
Highlights
Propofol is a kind of fat-soluble, rapid short-acting intravenous anesthetic, which has the advantages of quick onset, short duration, and quick recovery
The muscle tissue was separated through a median incision in the neck, and the carotid artery sheath was exposed along the right side of the trachea. e right vagus nerve trunk was separated with a glass minute hand under an operating microscope, and the peripheral end was pinched. e surrounding nerve was moisturized with a warm paraffin film to prevent nerve dryness and insulate from the surrounding tissue. e vagus nerve was placed on a platinum electrode (2 mm apart) to guide the discharge, and the vagus nerve was immersed in warm paraffin oil
As a kind of fat-soluble, rapid short-acting intravenous anesthetic, propofol has the advantages of quick onset, short duration, and quick recovery, which is suitable for rapid induction and maintenance in general anesthesia
Summary
Propofol is a kind of fat-soluble, rapid short-acting intravenous anesthetic, which has the advantages of quick onset, short duration, and quick recovery. It has gradually become the preferred drug for clinical induction and maintenance of anesthesia and has been widely used in various surgical anesthesia and can significantly reduce the occurrence of perioperative adverse events [1, 2]. Propofol-induced bradycardia has been recognized for several years, the pathophysiologic mechanism is not completely understood. Some studies showed that the decrease of heart rate induced by propofol could not be completely explained by the effect of the central vagus nerve, that is, propofol may have a direct inhibitory effect on the sinoatrial (SA) node [5, 6]
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