The use of monoamine oxidase inhibition to estimate megakaryocyte-platelet regeneration time (MPRT).
The megakaryocyte-platelet regeneration time (MPRT) was measured in 16 normal subjects after irreversible monoamine oxidase (MAO) inhibition. When ten subjects were given a single 20 mg dose of Parnate (tranylcypromine) the mean MPRT was 242 +/- 20 hours (linear model) or 212 +/- 22 hours (weighted mean model) with a mean %-linearity of 75 +/- 22%. The renewal of platelet MAO activity was initially retarded for about 2 days, suggesting that inhibition of megakaryocyte MAO had occurred. Six subjects who had taken MAO inhibitors daily for 1-6 months gave longer MPRT values (274 +/- 57 hours (lin.) or 246 +/- 67 hours (w. m.)), but the differences between the groups were not statistically significant. The single-dose MPRT results agree well with those obtained using the irreversible inhibition of cyclo-oxygenase by aspirin, but exceed the platelet life-spans estimated using radiochemical methods by about 24-36 hours. Platelet serotonin levels did not change significantly after a single dose of Parnate, but supine systolic blood pressure rose by 9 +/- 7 mm Hg (p less than 0.01) 24 hours after the dose. Estimation of MPRT by MAO inhibition is a useful alternative to the aspirin method but screening of subjects and clinical supervision is needed to avoid hypertensive complications.
Chamberlain
K G
KG
University of Melbourne, Department of Medicine, St. Vincent's Hospital, Victoria, Australia.
Tong
M
M
Chiu
E
E
Penington
D G
DG
D000284:Administration, Oral; D000328:Adult; D001241:Aspirin; D001792:Blood Platelets / Q000166:cytology* / Q000201:enzymology; D001794:Blood Pressure / Q000187:drug effects; D002455:Cell Division; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology*; D008995:Monoamine Oxidase / Q000097:blood; D008996:Monoamine Oxidase Inhibitors / Q000009:adverse effects; D013997:Time Factors
D008996:Monoamine Oxidase Inhibitors; D008995:Monoamine Oxidase; D001241:Aspirin