Effect of sympathomimetic amines on intramyocardial pressure in the rabbit

¹ Department of Physiology, University of London, King's College, London, England

Intramyocardial pressure has been measured in rabbits by means of a small inflatable latex balloon inserted into the myocardium of the left ventricle. The mean maximum intramyocardial pressure was found to be of the order of the aortic diastolic pressure. Adrenaline and isoprenaline infusion increased the maximum intramyocardial pressure; noradrenaline was without effect. Differential pressure plots of aortic and intramyocardial pressure against time showed that the increase in intramyocardial pressure produced by adrenaline and isoprenaline was matched by at least an equal increase in aortic systolic pressure. The same linear relationship was found when the total area under the curves (i.e., a function of flow) was plotted against the aortic diastolic pressure in controls and during infusion with sympathomimetic amines.