Two series of derivatives of N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), including a dechlorinated analog of W-7 (W-5) and various aminoalkyl chain analogs of W-7 (A-3, A-4, A-5, I-240, A-6) were synthesized and their structure-activity relationships with calmodulin antagonistic actions and their potencies in inhibiting human platelet aggregation in vitro were investigated. Their binding affinities to calmodulin in the presence of 100 microM Ca2+ were dependent both on the chlorination of the naphthalene ring and on the length of aminoalkyl chain. The ability of these derivatives to inhibit Ca2+-dependent phosphorylation of 20,000-dalton myosin light chain from platelets correlated well with the magnitude of their binding affinity to calmodulin. W-7(10-100 microM) inhibited in a dose-dependent manner platelet aggregation induced by collagen (2 micrograms/ml), ADP (5 microM), epinephrine (1 microgram/ml), sodium arachidonate (0.83 mM), thrombin (0.125 U/ml), and A-23187 (10 microM). The IC50 value (concentration producing 50% inhibition of aggregation) of W-7 was lower in arachidonate- and collagen-induced aggregation than in ADP- or epinephrine-induced aggregation. A good correlation between the potency in inhibition of collagen-induced aggregation by W-7 and its derivatives and their affinities to calmodulin was obtained (r = 0.94). Thus, the inhibitory mechanism of these compounds may be due to their effect on Ca2+-calmodulin-dependent processes, such as 20,000-dalton myosin light chain phosphorylation. These data also support the hypothesis that the calmodulin-mediated system has an important role in platelet function.
M Nishikawa, H Hidaka
Usage data is cumulative from September 2023 through September 2024.
Usage | JCI | PMC |
---|---|---|
Text version | 153 | 0 |
108 | 16 | |
Scanned page | 280 | 1 |
Citation downloads | 34 | 0 |
Totals | 575 | 17 |
Total Views | 592 |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.