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Platelet aggregability in humans: contrasting in vivo and in vitro findings during sympatho‐adrenal activation and relationship to serum lipids
Author(s) -
LARSSON P. T.,
HJEMDAHL P.,
OLSSON G.,
ANGELIN B.,
HORNSTRA G.
Publication year - 1990
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1990.tb01876.x
Subject(s) - in vivo , platelet , ex vivo , epinephrine , endocrinology , medicine , platelet activation , in vitro , chemistry , cholesterol , biology , biochemistry , microbiology and biotechnology
. Platelet aggregability was studied in 18 healthy volunteers during mental stress (a colour word test; CWT) and low‐ and high‐dose adrenaline infusions using an ex vivo technique (filtragometry) and conventional in vitro aggregometry. CWT and high‐dose adrenaline (3–4 nmol 1 ‐1 in plasma) shortened filtragometry readings, suggesting increased platelet aggregability in vivo . Low‐dose adrenaline had no effect despite higher adrenaline levels in plasma (0.9 nmol I ‐1 ) than during CWT (0.4 nmol I ‐1 ). Platelet sensitivity to ADP in vitro was reduced following CWT and further reduced following adrenaline infusions. In vitro , adrenaline (50 nmol I ‐1 ) had little effect on platelet aggregation per se , but enhanced aggregability evoked by ADP (at ED 50 ). Adrenaline potentiation of ADP‐induced aggregation was enhanced after CWT, but was not related to filtragometry responsiveness to stress in vivo . Serum LDL‐cholesterol levels were inversely correlated to filtragometry readings at rest, suggesting an adverse influence on platelet aggregability in vivo. HDL‐cholesterol levels were inversely correlated to platelet sensitivity to ADP in vitro , suggesting a positive influence. Thus, sympathp‐adre‐nal activation enhances platelet aggregability in vivo (as assessed by ex vivo filtragometry), but adrenaline alone cannot explain the pro‐aggregatory effect of mental stress. Serum lipoprotein alterations associated with increased risk for atherosclerosis seem to enhance platelet aggregability. The conventional in vitro technique may poorly reflect platelet aggregability in vivo. ,