Abstract
Cytochalasins: Effects on Platelet Aggregation, Adenylate Cyclase and Membrane Transport Processes
Thrombosis and Haemostasis, Vol.34(2), p.917
Thrombosis and Haemostasis Vth Congress - Paris - 1975-07-21
1975
DOI: 10.1055/s-0039-1689577
Abstract
Cytoehalasins A and B (CA and CB) are fungal metabolites that inhibit cellular motility, platelet aggregation and clot retraction. CA differs from CB only in the substitution of a carbonyl in CA for a hydroxy in CB. This confers on CA reactivity towards thiol groups. We have studied the effects of CA and CB on various membrane functions of intact human platelets in citrated plasma. CA inhibited the uptake of adenosine and 5 HT without affecting intracellular nucleotide metabolism. CA (56 uM) but not CB increased the rate of adenine uptake from 11.7±0.2 to 80.1±04.4 pmoles/inin/10
8
platelets, while the affinity of the uptake mechanism was reduced (K
m
apparent increased from 0.12 ±0.01 to 1.31 ±0.12 uM). CA inhibited platelet aggregation induced by ADP at concentrations lower than those that blocked the shape change. CA (20–50 uM) abolished the inhibition by ADP of cyclic AMP accumulation in platelets exposed to PGE
1
and the phosphodiesterase inhibitor RA 233, whereas CB (170 uM) was inactive. This effect of CA was prevented but not reversed by 1 mM cysteine.
The observed actions of CA are similar to those of other thiol reagents but occurred at concentrations below that of plasma protein thiol, indicating a preferential reactivity of CA towards the platelet membrane.
(Supported by N. I. H. HL 14217.)
Details
- Title: Subtitle
- Cytochalasins: Effects on Platelet Aggregation, Adenylate Cyclase and Membrane Transport Processes
- Creators
- D. C. B. Mills - Temple UniversityD. E. Macfarlane - Temple University
- Resource Type
- Abstract
- Publication Details
- Thrombosis and Haemostasis, Vol.34(2), p.917
- Conference
- Thrombosis and Haemostasis Vth Congress - Paris - 1975-07-21
- Publisher
- Schattauer GmbH
- DOI
- 10.1055/s-0039-1689577
- ISSN
- 0340-6245
- eISSN
- 2567-689X
- Language
- English
- Date published
- 1975
- Academic Unit
- Internal Medicine; Hematology, Oncology, and Blood & Marrow Transplantation
- Record Identifier
- 9984360047402771
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