Abstract
Platelet adhesiveness and its aggregative function are regarded as most leading causative factors of cerebral infarction. However, the studies on the platelet retention rate in the aged subjects remain rather scanty in number. In this viewpoint, the author performed the investigation of the platelet retention rate in 490 cases over 60 years of age in the nursing home of the Tokyo Metropolitan Geriatric Hospital. The determination of the platelet retention rate was made by the Salzman method as modified by Yasunaga. Moreover, inhibitors of platelet such as acetyl salcylica cid, dipyridamola nd sulfinepyrasonew ere administered to the aged subjects. The long term administrationo f these drugs resulted in preventiono f cerebro-vascularc cidents.
The results obtained were as follows:
(1) The normal value of the platelet retention rate of the aged was 48.3 21.1% in the male group and 36.8 18.7% in the female group respectively.
(2) Related to the effecting factors on platelet retention rate :
1) The higher retention rate was observedi n the male group in comparisonto the female group. 2) There was no definite correlation between the platelet count and the retention rate, while the retention rate was well correlated with the hematocrit value.
3) The retention rate of the hypertensive subject was much higher than that of the normotensives ubjects.
4) The retention rate was much higher in the cold season than in the warm or hot season.
5) The retention rate of the smoker group was much higher than that of the non- smoker group.
(3) The administrationo f acentyls alicylica cid resulted in lowering of the retention rate. The tendencyb ecamem uch more prouncedw ith simultaneousa dministrationo f dipyridamola nd sulfinepyrasone.
(4) For the preventiono f the causationo f cerebral infarction, 0. 75 g of acetyl salcylica cid was given every other day for two years, and a follow-up study was made. The observation revealed cerebral infarction in 4 cases out of 83 in the control group, while only 1 case was observedi n the drug-administeredg roup, which suggesteda slight effect of preventingo f these drugs on cerebral infarction.
