Effect of atropine or atenolol on cardiovascular responses to novelty stress in freely-moving rats.
Cardiac hemodynamic mechanisms involved in cardiovascular responses to stress were studied in conscious, freely-moving female spontaneously hypertensive rats exposed for 15 min to an open-field. When pretreated with saline, the rats displayed a rapid rise in blood pressure, heart rate, aortic dP/dt and locomotor activity. In rats pretreated with 0.5 mg/kg of methylatropine, the tachycardia was slightly, but significantly reduced. In rats pretreated with 1 mg/kg of atenolol, the tachycardis and rise in dP/dt were markedly reduced. These data suggest that the cardiac responses to stress include predominantly cardiac sympathetic activation and a minor component of vagal withdrawal.
Neuropharmacology Laboratory, Baker Medical Research Institute, Prahran, Melbourne, Australia. m.vandenbuuse@papyrus.mhri.edu.au
Maarten
M
van den Buuse
D000818:Animals; D001262:Atenolol / Q000494:pharmacology*; D001285:Atropine / Q000494:pharmacology*; D001522:Behavior, Animal / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects*; D005106:Exploratory Behavior / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D009043:Motor Activity / Q000502:physiology; D010276:Parasympatholytics / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D013312:Stress, Physiological / Q000139:chemically induced / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology; D013565:Sympatholytics / Q000494:pharmacology*; D013686:Telemetry; D014630:Vagus Nerve / Q000187:drug effects / Q000503:physiopathology
D010276:Parasympatholytics; D013565:Sympatholytics; D001262:Atenolol; D001285:Atropine