Cardiovascular effects of tubocurarine in man

The cardiovascular effects of tubocurarine in patients anaesthetised with thiopentone or ketamine have been compared, using volume-pulse finger plethysmography, electrocardiography, sphygmomanometry and impedance cardiography for the clinical assessments. Tubocurarine potentiates the arterial hypotensive effect of thiopentone and reverses the hypertensive action of ketamine. It also prevents the dysrhythmic (adrenergic) reaction of the heart to orotracheal intubation and has less effect on the positive chronotropic and inotropic reactions thereto. Hypotensive doses of tubocurarine in patients anaesthetised with thiopentone do not prevent reflex constriction of the finger blood vessels in response to surgical stimuli (orotracheal intubation) which means that the drug is not a sympathetic ganglion blocker in man. It is concluded that tubocurarine is a myocardial depressant which acts, like verapamil, as a calcium ion antagonist.