An indirect approach of the amount of invaginated platelet membrane has been provided by size measurements of platelets submitted to an hypotonic shock. We investigated this new morphological parameter in 15 normal subjects and in 11 ITP.Platelet volume was measured by the electronic method (Coulter counter, channelyser C 1000) on EDTA-PRP and on EDTA-PRP diluted with distilled water. One min. after dilution, paraformaldehyde (final concentration 0.08%) was added to prevent any return to the initial volume by an active process. Platelet lysis was quantified by LDH assay. Isoton was diluted in the same proportion. Arithmetic mean platelet volume (MPV) was calculated ; graphic analysis of the data allowed to determine the mode and the standard deviation (SD) of the log volume distribution.An inverse linear relationship between MPV and the log of osmolarity was observed. The maximum MPV increase without any detectable platelet lysis was obtained at 120 m Osm. For lower osmolarities a progressive lysis occured without further volume increase.Macrothrombocytosis and increased SD of the log volume distribution were found in undiluted ITP-PRP (12.2 fl and 0.31 respectively versus 9.2 fl and 0.27 in controls). After hypotonic treatment, the MPV increased in ITP and controls (respectively 17.2 fl and 15.9 fl) but the relative increase was lower in ITP than in controls (42% and 63% respectively) ; the SD of the log volume distribution was unmodi fied.These results suggest that large platelets occuring in ITP possess a reduced amount of invaginated plasma membrane.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.