title: Spectral analysis of intercycle heart fluctuations in Xenopus laevis, conscious or spinalized, treated with calcium channel blockers. Part I.
abstract: 1. In this study, electrocardiographic second lead tracings were recorded and analyzed online and offline in the conscious and spinalized Xenopus laevis under control conditions and after treatment with at least two effective doses of racemic diltiazem, nifedipine and racemic verapamil hydrochlorides. 2. Heart rates (HR) and intercycle heart rate power spectra (IHRPS) were calculated in the various experimental conditions. 3. Dose-dependent bradycardia was found in most cases, which was associated with dose-related increases in the overall dynamic range of the largest peak of HR variability (increased IHRPS), this being particularly marked at the higher nifedipine dose. The frequency position of the largest peak was unchanged in the spinalized preparation, as well as in the various treatments. 4. These findings may contribute toward a more complete pharmacodynamic definition of calcium channel blockers in their current therapeutic use.
authors.affiliation: I.M.O.-Institute of Experimental and Clinical Medicine, University of Ancona Medical School, Italy. ANIMO@POPCSI.UNIAN.IT
authors.forename: M
authors.initials: M
authors.lastname: Bernardi
authors.forename: R
authors.initials: R
authors.lastname: Deslauriers
authors.forename: J
authors.initials: J
authors.lastname: Docherty
authors.forename: C
authors.initials: C
authors.lastname: Rossi
authors.forename: L
authors.initials: L
authors.lastname: Rossini
authors.forename: P
authors.initials: P
authors.lastname: Rossini
authors.forename: C
authors.initials: C
authors.lastname: Tonnini
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003655:Decerebrate State / Q000503:physiopathology*; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography / Q000187:drug effects*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D009543:Nifedipine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D002121:Calcium Channel Blockers; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine