[Electrocardiographic functional diagnosis of the autonomic nervous system in cattle. 1. Electrocardiographic determination of maximum dose for the beta-adrenergic substance isoprenaline].

Reference is made to the importance of functional diagnosis of the autonomic nervous system in cattle, and a concept is described by which higher methodological reliability should be obtainable for intra-organic diagnosis of sympathetic nerve activity. What is needed, among others, is to eliminate the autonomous cardiac effect through pharmacological blockade by means of the parasympathetic atropine and the beta-receptor blocker propanolol. The beta-adrenergic substance isoprenaline, required to estimate propranolol blocking action upon the beta-adrenegic receptors, then was injected through indwelling catheters to the external jugular veins of cattle. The doses were between 50 microgram and 560 microgram. Isoprenaline doses between 200 microgram and 250 microgram were established as maximum doses by electrocardiographic examination, determination of heart rate, and clinical observation. Such maximum isoprenaline doses were found to be suitable for checking the extent to which beta-adrenergic blockade of the heart has been caused by beta-receptor blockers. However, sub-maximum isoprenaline doses of something between 100 microgram and 150 microgram should be used to establish the extent to which beta-receptors have caused relaxation of smooth musculature.