Berkson, Joseph

A fluorometric method was used to quantitate plasma epinephrine and norepinephrine during hemorrhagic and anaphylactic shock in healthy adult dogs anesthetized with pentobarbital. Arterial plasma was analyzed before and after hemorrhage in four dogs. Loss of approximately 18% of blood volume through rapid arterial bleeding caused no remarkable change in pressor amines. Loss of approximately one-third of the total blood volume decreased the mean arterial pressure by a range of 56–81% and invariably caused increased concentration of plasma pressor amines. The average concentration of epinephrine increased from 1.0 to 7.8 µg/1. of plasma, and that of norepinephrine increased from 2.5 to 3.6 µg. Additional bleeding caused further increase of plasma pressor amines. Seven dogs were given egg white intravenously to sensitize them. Subsequently, whenever a severe reaction (hypotension, bradycardia and respiratory depression) resulted from intravenous administration of egg white, venous plasma pressor amines increased. The average concentration of epinephrine increased from 0.7 to 7.7 µg/1. of plasma; norepinephrine increased in three dogs but remained unchanged or decreased in the remaining animals. Without a preceding ‘shock’ reaction, change in concentration of epinephrine-like substance was unremarkable. Intravenous administration of 1 mg of histamine base produced hypotension and usually slight increase of plasma pressor amines.

Fluorescent quantitation of epinephrine and norepinephrine in plasma of patients suspected of having pheochromocytomas is of considerable diagnostic value. The concentrations of these pressor amines in normal subjects, patients with various diseases with and without hypertension, and 13 patients with pheochromocytomas are reported. In all patients with pheochromocytomas and sustained hypertension the concentrations of pressor amines were significantly elevated. However, in patients with paroxysmal hypertension secondary to pheochromocytomas the pressor amine concentrations may be unelevated when the blood pressures are normal. In this latter group provocative tests with intravenous histamine are indicated to induce hypertension prior to quantitating pressor amines.