EFFECTS OF ISOPROTERENOL ON PERIPHERAL VENOUS TONE AND TRANSMURAL RIGHT ATRIAL PRESSURE IN MAN*

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Abstract
Right atrial, intrapleural (esophageal) and transmural right atrial pressure were recorded simultaneously with end-expiratory CO2 concentration and ventilation before and during intravenous infusion of isoproterenol. Despite mild hyperventilation in each experiment intrapleural pressure changes were insignificant. The regularly observed fall in transmural pressure was caused by the fall in atrial pressure. In other experiments forearm venous tone and pressure were measured before and during isoproterenol infusion into a foot vein. Venous pressure fell in most tests but venous constriction occurred regularly. The large shift of blood from the forearm which occurred in these experiments was caused primarily by the venous constriction and not by the fall in intraluminal pressure.