Blood cell aggregation and screen filtration pressure.

Abstract

Changes in the microcirculation of the conjunctiva were compared with the screen filtration pressure (SFP) of venous blood in presumed normal subjects and in others with known systemic disease. The presence of arteriolar aggregation and of other circulatory abnormalities was not attended by significantly different mean SFP values. When, however, 2.5 µg of adenosine diphosphate (ADP) per milliliter were added to blood in vitro 20 to 30 seconds before the SFP determination, the SFP increased. In subjects with normal microcirculation, the increase was slight; in those with abnormal circulation, it was marked. When abnormal changes in the circulation were present, or ADP potentiation was high, there was an increase in the spread of control SFP values. Also when the ADP potentiation was high, the control SFP values were slightly higher than when the SFP potentiation was low. Two serotonin antagonists did not prevent or decrease the increase in SFP by ADP.