Relationship between red blood cell potassium and plasma digitoxin concentrations in intoxicated patients.
After severe acute self-poisoning by cardiac glycosides, significant and persistent depletion of red blood cell K+ due to inhibition of Na+K+ ATPase is seen. Because of a delay between the time course of plasma digitalis concentrations and that of red blood cell K+ depletion, no direct relation exists between the two, and RBC K+ has hitherto not been considered useful as prognostic indicators of clinical outcome. In an effort to solve this problem, red blood cell K+ was measured by atomic absorption spectrophotometry and plasma digitoxin concentration assayed in six patients admitted to an intensive care unit after digitoxin self-poisoning. Using the effect compartment model of Sheiner, a relationship based on a sigmoid Emax model was able to relate the digitoxin concentration at the action site to red blood cell K+ depletion. Thus the duration of red blood cell K+ depletion could be predicted from two relative simple in vitro assays. Since RBC K+ is a marker of the inhibition of Na+K+ ATPase by digitoxin, this method could be of use for the management of patients self-poisoned with digitalis.
Urtizberea
M
M
INSERM U 26, Fernand Widal Hospital, Paris, France.
Rochdi
M
M
Sabouraud
A
A
Bismuth
C
C
Scherrmann
J M
JM
D000328:Adult; D004074:Digitoxin / Q000097:blood* / Q000506:poisoning*; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011041:Poisoning / Q000097:blood; D011188:Potassium / Q000097:blood*; D013406:Suicide, Attempted
D004074:Digitoxin; D011188:Potassium