Platelet-Activating Factor as a Modulator of Cardiac and Coronary Functions
Platelet-activating factor (PAF) is a phospholipid that is produced by white blood cells and platelets (Demopoulos et al., 1979; Benveniste et al., 1982). It is released from these cellular elements during systemic anaphylaxis or stimulation by IgE or nonimmune stimuli (e. g., calcium ionophore) in vitro. Systemic anaphylaxis is accompanied by severe cardiovascular decompensation, which was previously attributed to histamine release. However, histamine antagonists cannot block the cardiovascular consequences of systemic anaphylaxis. Recently, it was shown that purified PAF (l-O-hexadecyl-2-acetyl-sn-glyceryl-3-phosphocholine) can produce anaphylacticlike hypotension in experimental animals (Feuerstein et al., 1982; Benveniste et al., 1983; Halonen et al., 1980). Moreover, platelets were also associated with nonimmune pathophysiological processes: aggregation and thrombus formation on injured blood vessels. Thus, PAF may play a significant role in mediating the sequelae of platelet/blood vessel interactions, e. g., platelet-mediated coronary constriction. Since the heart shows profound pathological changes in anaphylaxis (Zavecz and Levi, 1977; Cappuro and Levi, 1975), and platelet-related coronary spasm is suspected in patients suffering from ischémic heart disease, experiments (Addonazio et al., 1982) were designed to study the direct effect of PAF on cardiac and coronary functions in the intact domestic pig heart.
KeywordsLeave Anterior Descend Platelet Activate Factor Coronary Blood Flow Coronary Resistance Systemic Anaphylaxis
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