Using the direct observation technique in situ of mesenterial blood vessels of rabbits under the microscope, the intravenous administration of a small amount of adrenaline in a dose like 0.1, 1.0, 10.0μg per kg was found to induce a transient damage to the “silicone-like property” of blood vessels, i.e. a transient swelling and stickiness of endothelial cells to platelets and leucocytes often forming platelet or platelet-leucocyte thrombi. Such evidences were repeatedly produced in the same animal by successive administration and were cinematographed. In accordance with these evidences the number of circulating platelets decreases immediately, i.e. 5-30 minutes after the injection of 0.1-1.0μg per kg of adrenaline and at the same time the blood coagulation time was shortened.
In man the intravenous injection of 0.1μg per kg of adrenaline was found to induce similar changes as in rabbits, i.e. immediate and transient decrease in the number of circulating platelets and abrupt and transient shortening of the blood coagulation time.
On the other hand the intravenous administration of noradrenaline in the same dose in man and rabbit was found to be less effective in regard to the above-mentioned effects.

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Nialamide was found to protect the blood vessels of man and rabbit from the damages to their “silicone-like property” of the endothelial cells by major arteriosclerogenic substances.
Pretreatment orally with 100mg of nialamide was found to prevent in all 9 animals the swelling of endothelial cells, appearance of stickiness of these cells to platelets and leucocytes and formation of white thrombi by major three arteriosclerogenic substances, adrenaline (0.1-50.0μg per kg administered intravenously), cholesterol (3gm in 6gm of lanolin per kg orally), and bacterial polysaccharide (1mg per kg, intravenously), by vital and microscopic observations of the mesenterial blood vessels in situ.
Pretreatment with 10-100mg of nialamide prevents the abrupt decrease in the number of circulating platelets by 0.1-1μg per kg of intravenous adrenaline or by oral cholesterol (3gm in 6gm of lanolin per kg) in all 21 animals. The shortening of the blood coagulation time by 1μg per kg of adrenaline was abolished by nialamide pretreatment, and that by large amount of cholesterol was diminished.
The abrupt decrease in the number of circulating platelets and the shortening of the blood coagulation time, which is regularly encountered by the intravenous injection of 0.1μg per kg of adrenaline or by the oral administration of 90cc of fresh cream plus 5g of butter in man were also found to be prevented by oral pretreatment with 100mg of nialamide 2 hours before the test or by daily administration of 75mg of nialamide in all 12 adults.
The rapidly acting and long lasting antithromboembolic effect of nialamide in man and animal, which was discovered in this experiment, may throw a promising light on the problem of the protection of arteriosclerotic and thromboembolic problems in human beings.

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