title: Effects of thrombin, acetyl salicylic acid and prostaglandins on spontaneous efflux of norepinephrine and beta-thromboglobulin from platelets in calcium/magnesium deficient environment.
abstract: The effect of different substances on the spontaneous efflux of 14C-norepinephrine (14C-NE) and beta-thromboglobulin (beta TG) from platelets in Ca2+ - and Mg2+ - free buffer was tested. Addition of increasing concentrations of thrombin (0.015-0.625 U/ml) resulted in an immediate increase of 14C-NE detectable in the supernatants, but the slopes of the efflux curves from 10 min after thrombin addition were almost identical and parallel with the slope before thrombin addition. Also beta-thromboglobulin was steadily released after thrombin addition. Prostaglandin E1 and prostacyclin in concentrations that gave a 30-fold increase in cAMP accumulation resulted in a moderate decrease in efflux of 14C-NE from 10 to 30 min but did not influence the efflux thereafter up to 80 min. Acetyl salicylic acid in vivo and in vitro (200-500 mumol/l) did not influence the efflux of 14C-NE or beta TG. The conclusions are that factors known to exert considerable effects on aggregation, desaggregation and acute release produce only transitory effects in a Ca2+ - and Mg2+ - free environment and that the basal efflux of alpha-granule components seems to be a stable process.
mesh_terms: D000527:Alprostadil; D001241:Aspirin / Q000494:pharmacology*; D001609:Beta-Globulins / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium; D011464:Epoprostenol / Q000494:pharmacology*; D006801:Humans; D008274:Magnesium; D009638:Norepinephrine / Q000378:metabolism*; D011453:Prostaglandins / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology*; D001620:beta-Thromboglobulin / Q000378:metabolism*
chemical_list: D001609:Beta-Globulins; D011453:Prostaglandins; D011458:Prostaglandins E; D001620:beta-Thromboglobulin; D011464:Epoprostenol; D013917:Thrombin; D000527:Alprostadil; D008274:Magnesium; D001241:Aspirin; D002118:Calcium; D009638:Norepinephrine