Loss of platelet alpha 2-adrenergic receptors during simulated extracorporeal circulation: prevention with prostaglandin E1
Cardiopulmonary bypass prolongs bleeding time and increases postoperative blood loss. During in vitro recirculation in an extracorporeal circuit containing a membrane oxygenator and primed with fresh heparinized human blood, the authors previously observed thrombocytopenia, impaired platelet aggregation, and depletion of granular contents, all of which were prevented with prostaglandin E1 (PGE1). To investigate these changes further, they studied the number and affinity of platelet alpha 2-adrenergic receptors by measuring the binding of /sup 3/H-yohimbine. Before recirculation, they found 235 alpha 2-adrenergic receptors per platelet, a Kd of 3.37 nmol/L, complete aggregation with 1.04 mumol/L epinephrine, and a platelet count of 281,000 microliters/sup -1/. After 2 minutes of recirculation, 9.44 mumol/L epinephrine was required to produce complete aggregation, and the platelet count was 104,000 microliters-1 (44% of control). After 2 hours of recirculation, the platelet count had increased to 123,000 microliters/sup -1/. However, epinephrine did not induce platelet aggregation even at 100 mumol/L. Moreover, alpha 2-adrenergic binding sites were not detectable, and affinity for yohimbine could not be calculated. Two minutes after PGE1 0.3 mumol/L was added to the circuit, platelet numbers, response to epinephrine, alpha 2-adrenergic binding sites per platelet, and affinity for yohimbine were not significantly different from control values. At 2 hours, the number of alpha 2-adrenergic sites was not significantly changed from control, but the affinity of yohimbine for platelets was significantly decreased 2.5-fold.
- Research Organization:
- Temple Univ. Health Sciences Center, Philadelphia, PA
- OSTI ID:
- 5127327
- Journal Information:
- J. Lab. Clin. Med.; (United States), Journal Name: J. Lab. Clin. Med.; (United States) Vol. 5; ISSN JLCMA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ADRENALINE
AGGLOMERATION
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOLOGICAL EFFECTS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD PLATELETS
BODY FLUIDS
CARDIOTONICS
CARDIOVASCULAR AGENTS
CONFIGURATION INTERACTION
DRUGS
HORMONES
LABELLED COMPOUNDS
MATERIALS
NEUROREGULATORS
PROSTAGLANDINS
RECEPTORS
STEROID HORMONES
SYMPATHOMIMETICS
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