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Some variations in success rate exist between dentists the most dental procedures under local anaesthetic in general practice were assessed as being comfortable or better by both dentists and patients.

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Australia1 Arterial blood pressure, heart rate and cardiac contractility were measured in pentobarbitoneanaesthetized mongrel dogs and in conscious, instrumented dogs. 2 In anaesthetized dogs (n = 5), dose-response curves were obtained by intravenous infusion of increasing doses of dopexamine (5-20 fg kg-' min -). Infusions were administered three times to each animal to determine whether the responses were reproducible. Dopexamine increased heart rate and myocardial contractility and decreased blood pressure. The dose-response curves for dopexamine did not differ significantly over time. 3 In a second group of dogs (n = 6), dose-response curves (5-20 mg kg' min') were obtained as above and repeated after the administration of amitriptyline (2 mg kg-', i.v.). Amitriptyline caused a non-significant reduction in the inotropic and chronotropic responses to dopexamine.4 Control dose-response curves for dopexamine (5-50f.gkg-'min-1) were similarly obtained in a third group of dogs (n = 6), and repeated after bilateral vagotomy and sympathetic denervation of the heart. In these animals, a third dose-response curve for dopexamine was obtained after the administration of ICI 118551 (0.2 mg kg-', followed by 0.2mg kg-' h-'). The chronotropic response to dopexamine was significantly reduced after cardiac denervation. There was a small, non-significant reduction in the inotropic and depressor responses after denervation. Administration of ICI 115881 significantly reduced both the inotropic and chronotropic response to dopexamine and caused a non-significant reduction in the depressor response.5 The effect of raclopride (0.2 pmol kg-', p.o.) was investigated by comparison of the dose-response curves for dopexamine in a control group of dogs (n = 6) to those obtained in dogs which had been pretreated with raclopride (n = 5). Raclopride had no significant effect on the cardiovascular responses to dopexamine. 6 In conscious, instrumented dogs (n = 5), pretreated with raclopride, dose-related positive inotropic and chronotropic and depressor responses to dopexamine infusions were recorded. The chronotropic responses in conscious animals were significantly greater than those in the anaesthetized animals. 7 The results of this study indicate that both the positive inotropic and chronotropic actions of dopamine are due to a combination of direct, P2-adrenoceptor-mediated effects and the baroreceptor reflex response to the depressor action of the drug.