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One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function

View Article: PubMed Central - PubMed

ABSTRACT

Background: Despite public awareness that tobacco secondhand smoke (SHS) is harmful, many people still assume that marijuana SHS is benign. Debates about whether smoke‐free laws should include marijuana are becoming increasingly widespread as marijuana is legalized and the cannabis industry grows. Lack of evidence for marijuana SHS causing acute cardiovascular harm is frequently mistaken for evidence that it is harmless, despite chemical and physical similarity between marijuana and tobacco smoke. We investigated whether brief exposure to marijuana SHS causes acute vascular endothelial dysfunction.

Methods and results: We measured endothelial function as femoral artery flow‐mediated dilation (FMD) in rats before and after exposure to marijuana SHS at levels similar to real‐world tobacco SHS conditions. One minute of exposure to marijuana SHS impaired FMD to a comparable extent as impairment from equal concentrations of tobacco SHS, but recovery was considerably slower for marijuana. Exposure to marijuana SHS directly caused cannabinoid‐independent vasodilation that subsided within 25 minutes, whereas FMD remained impaired for at least 90 minutes. Impairment occurred even when marijuana lacked cannabinoids and rolling paper was omitted. Endothelium‐independent vasodilation by nitroglycerin administration was not impaired. FMD was not impaired by exposure to chamber air.

Conclusions: One minute of exposure to marijuana SHS substantially impairs endothelial function in rats for at least 90 minutes, considerably longer than comparable impairment by tobacco SHS. Impairment of FMD does not require cannabinoids, nicotine, or rolling paper smoke. Our findings in rats suggest that SHS can exert similar adverse cardiovascular effects regardless of whether it is from tobacco or marijuana.

No MeSH data available.


Related in: MedlinePlus

Impairment of FMD by 1 minute of exposure to marijuana SHS. See Table for group mean FMD and diameter values. A, FMD and baseline artery diameter in rats exposed to chamber air (0.73±0.055 μg/m3; n=8), high‐dose marijuana SHS (584±16 μg/m3; n=10), or high‐dose THC‐free marijuana SHS (608±13 μg/m3; n=8); errors are SD. Because smoke levels did not decline substantially over 1 minute, the average concentration over time is listed. Colors track individual rats through the FMD graphs and corresponding diameter graphs. FMD in rats exposed to SHS from regular marijuana or THC‐free marijuana decreased, whereas baseline diameter increased significantly by 8.2% for regular marijuana and 9.2% for THC‐free marijuana. B, Waiting for 25 minutes post‐end of exposure before FMD measurement (562±16 μg/m3; n=7) revealed substantial impairment of FMD without concomitant baseline vasodilation. C, FMD impairment for at least 90 minutes (617±10 μg/m3; n=8) with no significant improvement. Removal of 1 potential outlier (red line) would result in a significant partial improvement at 90 minutes postexposure relative to 30 minutes (P=0.019), but all postexposure values would still be depressed relative to pre‐exposure with P<0.0005. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke; THC, tetrahydrocannabinol.
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jah31602-fig-0004: Impairment of FMD by 1 minute of exposure to marijuana SHS. See Table for group mean FMD and diameter values. A, FMD and baseline artery diameter in rats exposed to chamber air (0.73±0.055 μg/m3; n=8), high‐dose marijuana SHS (584±16 μg/m3; n=10), or high‐dose THC‐free marijuana SHS (608±13 μg/m3; n=8); errors are SD. Because smoke levels did not decline substantially over 1 minute, the average concentration over time is listed. Colors track individual rats through the FMD graphs and corresponding diameter graphs. FMD in rats exposed to SHS from regular marijuana or THC‐free marijuana decreased, whereas baseline diameter increased significantly by 8.2% for regular marijuana and 9.2% for THC‐free marijuana. B, Waiting for 25 minutes post‐end of exposure before FMD measurement (562±16 μg/m3; n=7) revealed substantial impairment of FMD without concomitant baseline vasodilation. C, FMD impairment for at least 90 minutes (617±10 μg/m3; n=8) with no significant improvement. Removal of 1 potential outlier (red line) would result in a significant partial improvement at 90 minutes postexposure relative to 30 minutes (P=0.019), but all postexposure values would still be depressed relative to pre‐exposure with P<0.0005. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke; THC, tetrahydrocannabinol.

Mentions: Group Means for Graphs in Figures 2, 3, 4, 5 Through 6


One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function
Impairment of FMD by 1 minute of exposure to marijuana SHS. See Table for group mean FMD and diameter values. A, FMD and baseline artery diameter in rats exposed to chamber air (0.73±0.055 μg/m3; n=8), high‐dose marijuana SHS (584±16 μg/m3; n=10), or high‐dose THC‐free marijuana SHS (608±13 μg/m3; n=8); errors are SD. Because smoke levels did not decline substantially over 1 minute, the average concentration over time is listed. Colors track individual rats through the FMD graphs and corresponding diameter graphs. FMD in rats exposed to SHS from regular marijuana or THC‐free marijuana decreased, whereas baseline diameter increased significantly by 8.2% for regular marijuana and 9.2% for THC‐free marijuana. B, Waiting for 25 minutes post‐end of exposure before FMD measurement (562±16 μg/m3; n=7) revealed substantial impairment of FMD without concomitant baseline vasodilation. C, FMD impairment for at least 90 minutes (617±10 μg/m3; n=8) with no significant improvement. Removal of 1 potential outlier (red line) would result in a significant partial improvement at 90 minutes postexposure relative to 30 minutes (P=0.019), but all postexposure values would still be depressed relative to pre‐exposure with P<0.0005. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke; THC, tetrahydrocannabinol.
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jah31602-fig-0004: Impairment of FMD by 1 minute of exposure to marijuana SHS. See Table for group mean FMD and diameter values. A, FMD and baseline artery diameter in rats exposed to chamber air (0.73±0.055 μg/m3; n=8), high‐dose marijuana SHS (584±16 μg/m3; n=10), or high‐dose THC‐free marijuana SHS (608±13 μg/m3; n=8); errors are SD. Because smoke levels did not decline substantially over 1 minute, the average concentration over time is listed. Colors track individual rats through the FMD graphs and corresponding diameter graphs. FMD in rats exposed to SHS from regular marijuana or THC‐free marijuana decreased, whereas baseline diameter increased significantly by 8.2% for regular marijuana and 9.2% for THC‐free marijuana. B, Waiting for 25 minutes post‐end of exposure before FMD measurement (562±16 μg/m3; n=7) revealed substantial impairment of FMD without concomitant baseline vasodilation. C, FMD impairment for at least 90 minutes (617±10 μg/m3; n=8) with no significant improvement. Removal of 1 potential outlier (red line) would result in a significant partial improvement at 90 minutes postexposure relative to 30 minutes (P=0.019), but all postexposure values would still be depressed relative to pre‐exposure with P<0.0005. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke; THC, tetrahydrocannabinol.
Mentions: Group Means for Graphs in Figures 2, 3, 4, 5 Through 6

View Article: PubMed Central - PubMed

ABSTRACT

Background: Despite public awareness that tobacco secondhand smoke (SHS) is harmful, many people still assume that marijuana SHS is benign. Debates about whether smoke&#8208;free laws should include marijuana are becoming increasingly widespread as marijuana is legalized and the cannabis industry grows. Lack of evidence for marijuana SHS causing acute cardiovascular harm is frequently mistaken for evidence that it is harmless, despite chemical and physical similarity between marijuana and tobacco smoke. We investigated whether brief exposure to marijuana SHS causes acute vascular endothelial dysfunction.

Methods and results: We measured endothelial function as femoral artery flow&#8208;mediated dilation (FMD) in rats before and after exposure to marijuana SHS at levels similar to real&#8208;world tobacco SHS conditions. One minute of exposure to marijuana SHS impaired FMD to a comparable extent as impairment from equal concentrations of tobacco SHS, but recovery was considerably slower for marijuana. Exposure to marijuana SHS directly caused cannabinoid&#8208;independent vasodilation that subsided within 25&nbsp;minutes, whereas FMD remained impaired for at least 90&nbsp;minutes. Impairment occurred even when marijuana lacked cannabinoids and rolling paper was omitted. Endothelium&#8208;independent vasodilation by nitroglycerin administration was not impaired. FMD was not impaired by exposure to chamber air.

Conclusions: One minute of exposure to marijuana SHS substantially impairs endothelial function in rats for at least 90&nbsp;minutes, considerably longer than comparable impairment by tobacco SHS. Impairment of FMD does not require cannabinoids, nicotine, or rolling paper smoke. Our findings in rats suggest that SHS can exert similar adverse cardiovascular effects regardless of whether it is from tobacco or marijuana.

No MeSH data available.


Related in: MedlinePlus