Postprandial plasma triacylglycerols in rats under alpha 1-adrenergic blockade

The present studies evaluated the effect of prazosin, a selective alpha 1-adrenergic antagonist, on some metabolic determinants of triacylglycerol-rich lipoproteins. Plasma triacylglycerols (TG), TG secretion rate, TG removal rate, plasma insulin, and glucose were evaluated postprandially in animals fed a high-sucrose meal. In the fasted state plasma TG, glucose, and insulin concentrations were minimally affected by prazosin. There was a significant postprandial elevation in plasma TG levels that was larger after ingestion of a meal containing corn oil than after intake of a fat-free meal. Prazosin totally blunted the postprandial elevation in plasma TG independently of the presence (P < 0.004) or absence of dietary fat (P < 0.01). In the postprandial phase after ingestion of a fat-free, high-sucrose meal, prazosin decreased the rate of secretion of TG into the circulation (-54%, P < 0.0003) and accelerated twofold the clearance of an injected fat emulsion (P < 0.02). The postprandial elevations in plasma insulin and glucose were significantly potentiated by administration of prazosin before intake of the fat-free meal. These results indicate that prazosin prevented the postprandial elevation in plasma TG that followed the ingestion of a high-sucrose meal. The results also demonstrate that the alpha 1-blocker exerted its action both by decreasing TG secretion and by increasing the rate of removal of circulating TG.