Methods and Results  We exposed 8 rats/group to aerosol generated by two vaporizer systems using marijuana with varying THC levels, in a single pulsatile exposure session of 2 sec/min over 5 min, and measured changes in FMD. To model secondhand exposure, we exposed rats for 1 min to diluted aerosol approximating release of uninhaled Volcano aerosol into typical residential rooms. Exposure to aerosol from marijuana with and without cannabinoids impaired FMD by ~50%. FMD was similarly impaired by aerosols from Yocan, and from Volcano at both its standard temperature (185°C) and the minimum sublimation temperature of THC (157°C), even though the low-temperature aerosol condition did not effectively deliver THC to the circulation. Modeled secondhand exposure based on diluted Volcano aerosol also impaired FMD. FMD was not affected in rats exposed to clean air or water vapor passed through the Volcano system. 

Conclusions Acute direct exposure and modeled secondhand exposure to marijuana leaf vaporizer aerosol, regardless of cannabinoid concentration or aerosol generation temperature, impair endothelial function in rats comparably to marijuana smoke. Our findings indicate that use of leaf vaporizers is unlikely to reduce vascular risk burden of smoking marijuana.

For FMD data, raw ultrasound data were collected by an ultrasound transducer (Vevo 660 or Vevo 3100 LT; VisualSonics, Totonto, Canada). Ultrasound images were processed using an automated system (Brachial Analyzer; Medical Imaging Applications, Coralville, IA).