Cardiovascular and allied actions of xylazine and atropine in the unanaesthetized goat.
The cardiovascular effects of xylazine and atropine, separately and in combination, were studied in goats. Methylatropine was used to distinguish between the central and peripheral effects of atropine. Mean arterial blood pressure and heart rate were recorded, and the sedative effect and changes in respiration and salivation noted. Intravenous infusion of xylazine (2.4-80.0 micrograms/kg) decreased mean arterial blood pressure and heart rate in a dose-dependent manner. Single intravenous injections of both atropine sulphate (0.1 mg/kg) and methylatropine bromide (0.05 mg/kg) increased blood pressure and heart rate. After methylatropine, tachycardia lasted twice as long as after atropine. Following atropinization, a potentiated rise in mean arterial blood pressure was present during the infusion of xylazine (80 micrograms/kg). Xylazine-induced bradycardia was reversed by both atropine and methylatropine. The action of atropine is presumed to be primarily peripheral because of the similar effects with methylatropine. Xylazine-induced sedation was dose dependent. At the highest dose the goats were unable to stand for 30-60 min, respiration became irregular with periods of apnoea, and saliva started to drip a few minutes after infusion without increased salivation. Atropine had no visible effect on the sedation, pattern of respiration or saliva dripping effect of xylazine.
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D001286:Atropine Derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006041:Goats / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D010276:Parasympatholytics / Q000494:pharmacology; D012119:Respiration / Q000187:drug effects; D012472:Salivation / Q000187:drug effects; D013843:Thiazines / Q000494:pharmacology*; D014991:Xylazine / Q000494:pharmacology*
D001286:Atropine Derivatives; D010276:Parasympatholytics; D013843:Thiazines; D014991:Xylazine; D001285:Atropine; C006649:methylatropine