title: Comparison of negative inotropic and vasodilator effects of isradipine and nifedipine after complete autonomic blockade in ischemic heart disease.
abstract: The cardiodepressant and vasodilator effects of an intravenous (i.v.) infusion of 0.5 mg isradipine or 2 mg nifedipine were interindividually (10 vs. 10 patients) compared in a double-blind study in patients with stable coronary heart disease. To minimize vasodilation-induced autonomic reflex mechanisms, which may counterbalance negative inotropic effects after acute administration of calcium antagonists, i.v. autonomic blockade was produced by 0.2 mg/kg propranolol and 0.04 mg/kg atropine. Systemic hemodynamics were measured before and 15 min after the end of the 15-min calcium antagonist infusion. After administration of both drugs, heart rate (HR) decreased similarly during the observation period (isradipine from 93 +/- 10 to 88 +/- 9 beats/min and nifedipine from 84 +/- 9 to 79 +/- 6 beats/min, both p less than or equal to 0.01). The reduction in total peripheral resistance (TPR) was significantly (p less than or equal to 0.01) greater after isradipine (from 1,376 +/- 285 to 1,002 +/- 224 dynes s cm-5) than after nifedipine (1,258 +/- 262 to 1,112 +/- 225 dynes s cm-5). Between the two drugs, the difference in the reduction of afterload independent dP/dt40, determined by tip-manometry, reached borderline significance (p = 0.08) (isradipine from 1,197 +/- 258 to 1,157 +/- 225 mm Hg/s, NS and nifedipine 1,228 +/- 226 to 1,109 +/- 227 mm Hg/s, p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D001340:Autonomic Nerve Block; D003864:Depression, Chemical; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D017275:Isradipine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D017202:Myocardial Ischemia / Q000188:drug therapy* / Q000503:physiopathology; D009543:Nifedipine / Q000627:therapeutic use*; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D009543:Nifedipine; D017275:Isradipine