Abnormal XXXX handling by platelets in @entity715 .

@entity1 @entity1095 @entity1855 @entity6028 @entity49 @entity7914 @entity460 @entity141 @entity715
This study presents a quantitative comparison of the free cytoplasmic @entity460 concentration ([ @entity141 ]cyt) and the free concentration in the lumen of the dense tubules of the @entity1 platelet. The former was measured by the fluorescence of the high affinity indicator @entity6028 and latter by the fluorescence of @entity7914 (CTC). The CTC technique monitors @entity460 -CTC complex accumulation in the lumen of dense tubules and mitochondria when washed platelets were incubated in 2 mM @entity141 . Resting cytoplasmic and dense tubular @entity141 concentrations were studied in platelets from @entity1 suffering from venous and arterial @entity715 . Compared with normal controls (0.40 +/- 0.10, n = 54), the values of the @entity460 -CTC ratios were 0.68 +/- 0.19 (n = 16, p less than 0.005) in @entity49 ; 0.75 +/- 0.18 (n = 14, p less than 0.005) in cardiovascular accident; 0.84 +/- 0.18 (n = 6, p less than 0.005) in occlusive @entity1095 ; and 0.42 +/- 0.10 (n = 21, p greater than 0.1) in @entity1 controls. The dense tubular @entity141 levels for both @entity1 and controls were perfectly correlated with the cytoplasmic levels using an equation that assumes that the dense tubular free @entity460 concentration ([ @entity141 ]dt) has a second power dependence on [ @entity141 ]cyt. The abnormal @entity141 handling of platelets obtained from @entity715 @entity1 could be completely reversed by preincubation with the @entity460 channel blocker @entity1855 . These observations suggest that the primary @entity141 handling defect is the leakage through activated channels in the plasma membrane. The defect and the elevated resting [ @entity141 ]cyt and [ @entity141 ]dt are adequate to explain the observation of increased rates of collagen-activated aggregation in the above-mentioned group of @entity1 . The results can be explained by platelets from @entity715 @entity1 being exposed to activating factors in the circulation, resulting in @entity141 channel activation. Channel activation persists through the process of platelet isolation and washing and is manifested in higher measured values of [ @entity141 ]cyt and [ @entity141 ]dt in the "resting state." This would bring the platelet closer to its aggregation when aggregation-inducing agents are added. The CTC test is shown to be a useful and convenient means of detecting this abnormality.
