Collagen-induced platelet aggregation and release. II Critical size and structural requirements of collagen.
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Biomedical subjects
Publications and source records attributed to B Weksler.
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If altered platelet function contributes to poorly perfused zones of myocardium in patients with angina pectoris, then specific antiplatelet therapy might improve cardiovascular function and exercise performance. Exercise tolerance on a bicycle ergometer, heart rate-blood pressure product, and ischemic ECG changes at exercise end-point were compared before and during oral aspirin therapy (2.4 Gm. per day for 2 weeks) in 11 normal subjecs and in 11 patients with stable angina pectoris. Platelet aggregation threshold in response to ADP and epinephrine was measured. Untreated patients had increased platelet aggregability when compared to normal subjects...
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Human platelet acid extract obtained from both whole platelets and from isolated subcellular granules was partially purified by DEAE-cellulose chromatography and Sephadex gel filtration. The heat-stable, nondialyzable cationic protein fraction with a mol wt of approximately 30,000 produced a biphasic increase in vascular permeability in rabbit skin and also had antiheparin activity. The acute (15 min) increase in vascular permeability was blocked by prior treatment of the animal with antihistamine and was characterized histologically by edema of perivascular tissues and dilation of capillaries and veinules. The delayed (3 hr) permeability effect was not blocked by antihistamine and was characterized histologically by leukocytic infiltration into the skin. The experiments described suggest that human platelet lysosomal release of cationic proteins may increase vascular permeability by several mechanisms including endogenous histamine release as well as delayed chemotaxis.
A cationic protein extract obtained from isolated human platelet granules increased vascular permeability in mouse and rabbit skin. The permeability-enhancing effect was not inhibited by soybean trypsin and pancreatic trypsin inhibitor, methylsergide maleate, carboxypeptidase B, and C[unk]1 inactivator. Permeability-enhancing activity was blocked by prior treatment of challenged animals with antihistamine. The nondializable relatively heat-stable cationic granule protein extract possessed potent mastocytolytic activity. The experiments described suggest that human platelets exert a permeability-enhancing effect by lysosomal release of cationic proteins which cause histamine release from adjacent tissue mast cells.