title: An investigation of the cardiotoxic action of vancomycin in the isolated working rat heart.
abstract: The mechanism of cardiotoxic action of vancomycin was examined in preparations of isolated working rat hearts and spontaneously beating right atria. Vancomycin produced a concentration-dependent decrease in aortic flow, coronary flow and heart rate in the isolated working rat heart, with no significant effect on other haemodynamic parameters. At 5 mm, vancomycin produced a statistically significant decrease (compared with control values) in aortic flow (24.1 +/- 7.5%) and in the basal heart rate (34.3 +/- 3.5%) after 15 min incubation. Coronary flow was also reduced by 23.5 +/- 9.2%. Prolonged exposure of the preparation to 5 mm-vancomycin produced a marked time-dependent bradycardia accompanied by a time-dependent increase in the leakage of lactic dehydrogenase (LDH) into the perfusion medium. Moreover, a correlation (r = -0.94) was found between the time-dependent bradycardia and LDH leakage induced by Vancomycin. In the isolated spontaneously beating right atria pretreated with atropine, vancomycin (5 mm) also produced a time-dependent bradycardia similar to that found in the isolated working rat heart. Moreover, (45)Ca(2+)-flux studies indicated that vancomycin had no significant effect on the (45)Ca(2+) uptake into the right atrial muscle. These data suggest that: (1) vancomycin has a direct and acute cardiotoxic action at high concentrations (> 1 mm); (2) time-dependent bradycardia is a sensitive functional index for the cardiotoxicity induced by vancomycin; (3) the bradycardia elicited by vancomycin is due neither to the release of acetylcholine from the parasympathetic nerves innervating the heart nor to blockade of Ca(2+) entry.
authors.affiliation: Department of Investigative Toxicology, Smith Kline & French Laboratories, Research and Development Division, P.O. Box 1539, King of Prussia, PA 19406-0939, USA.
authors.forename: K F
authors.initials: KF
authors.lastname: Jim
authors.forename: W D
authors.initials: WD
authors.lastname: Matthews