Abstract 19538: Brief Exposure to Marijuana Secondhand Smoke Impairs Vascular Endothelial Function
Objectives: Despite general public awareness that tobacco secondhand smoke (SHS) is harmful, much of the public still regards marijuana SHS as benign. Because marijuana smoke and tobacco smoke are chemically and physically similar (other than nicotine and tetrahydrocannabinol (THC)), we tested this assumption by asking whether short exposure to marijuana SHS causes acute vascular endothelial dysfunction similar to that caused by tobacco SHS. Exposure to tobacco SHS impairs arterial flow-mediated dilation (FMD) in humans and rats.
Methods: We used a rat model to test the effects of secondhand marijuana smoke on FMD. We exposed anesthetized rats to marijuana SHS using a modified cigarette smoking machine, and measured FMD three times: before 30-min exposure (“pre”), 10 min after end of exposure (“post10”), and 40 min after end of exposure (“post40”). FMD was measured by micro-ultrasound measurements of femoral artery diameter before and after transient (5 min) surgical ligation of the common iliac artery. Concentrations of respirable suspended particles <2.5 μm (RSP) fell during exposure; exposure conditions are denoted by starting concentrations.
Results: Marijuana SHS starting at 667±62 μg/m3 RSP (n=8) caused FMD to fall from 7.5±0.94% (SEM) pre to 2.3±0.50% at post10 and 2.2±0.80 at post40 (P<0.01 for both post10 and post40 vs. pre, adjusted for multiple comparisons). SHS from placebo marijuana lacking THC starting at 671±49 μg/m3 RSP (n=7) similarly impaired FMD (9.9±1.4% pre, 4.3±0.64% post10 (p<0.01), 5.5±1.3% post40 (P<0.05)), confirming that impairment did not depend on the THC. In contrast, air in the exposure chamber (1.8±0.7 μg/m3 RSP; n=8) did not alter FMD (11.0±0.64% pre, 11.4±0.72% post10, 11.7±0.86% post40, P>0.70).
Conclusions: Marijuana and tobacco SHS impair endothelial function similarly under comparable exposure conditions. Public exposure to SHS should be avoided whether the source is tobacco or marijuana.
Author Disclosures: X. Wang: None. R. Derakhshandeh: None. S. Narayan: None. E. Luu: None. S. Le: None. O.M. Danforth: None. H.J. Rodriguez: None. R.E. Sievers: None. S.F. Schick: None. S.A. Glantz: None. M.L. Springer: None.
- © 2014 by American Heart Association, Inc.