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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

Experimental design for FMD measurement and smoke exposures. FMD was measured by micro‐ultrasound measurements of femoral artery diameter before and after transient (5 minutes) surgical occlusion of the common iliac artery. Anesthetized rats were exposed to SHS for varying durations and FMD was measured 3 times (before exposure, 10 minutes after end of exposure to evaluate impairment, and 30 minutes later to evaluate recovery). As described in the Results section for specific experiments, the smoke exposure was either for 30 minutes or 1 minute, and initial FMD impairment or baseline diameter changes were measured either within 10 minutes or 25 to 30 minutes after the end of exposure. In some cases, FMD recovery was assessed every 30 minutes over a total duration of 90 minutes. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke.
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jah31602-fig-0001: Experimental design for FMD measurement and smoke exposures. FMD was measured by micro‐ultrasound measurements of femoral artery diameter before and after transient (5 minutes) surgical occlusion of the common iliac artery. Anesthetized rats were exposed to SHS for varying durations and FMD was measured 3 times (before exposure, 10 minutes after end of exposure to evaluate impairment, and 30 minutes later to evaluate recovery). As described in the Results section for specific experiments, the smoke exposure was either for 30 minutes or 1 minute, and initial FMD impairment or baseline diameter changes were measured either within 10 minutes or 25 to 30 minutes after the end of exposure. In some cases, FMD recovery was assessed every 30 minutes over a total duration of 90 minutes. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke.

Mentions: For each experiment, a single cigarette was lit, smoked for 3 minutes, and extinguished, and particle concentration in the exposure chamber was adjusted until the desired RSP starting concentration was reached (Figure 1). At that time, an individual anesthetized rat, after baseline FMD measurement, was exposed for the specified duration and was then returned to the ultrasound system for postsmoke FMD measurement. Negative controls consisted of the same duration of exposure to nonsmoky air in the exposure chamber. As in our tobacco study,34 it took roughly 10 minutes after the end of the exposure period to prepare the rat for an initial postexposure FMD measurement. For some experiments, we measured FMD again 30 minutes later to evaluate recovery.


One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function
Experimental design for FMD measurement and smoke exposures. FMD was measured by micro‐ultrasound measurements of femoral artery diameter before and after transient (5 minutes) surgical occlusion of the common iliac artery. Anesthetized rats were exposed to SHS for varying durations and FMD was measured 3 times (before exposure, 10 minutes after end of exposure to evaluate impairment, and 30 minutes later to evaluate recovery). As described in the Results section for specific experiments, the smoke exposure was either for 30 minutes or 1 minute, and initial FMD impairment or baseline diameter changes were measured either within 10 minutes or 25 to 30 minutes after the end of exposure. In some cases, FMD recovery was assessed every 30 minutes over a total duration of 90 minutes. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015303&req=5

jah31602-fig-0001: Experimental design for FMD measurement and smoke exposures. FMD was measured by micro‐ultrasound measurements of femoral artery diameter before and after transient (5 minutes) surgical occlusion of the common iliac artery. Anesthetized rats were exposed to SHS for varying durations and FMD was measured 3 times (before exposure, 10 minutes after end of exposure to evaluate impairment, and 30 minutes later to evaluate recovery). As described in the Results section for specific experiments, the smoke exposure was either for 30 minutes or 1 minute, and initial FMD impairment or baseline diameter changes were measured either within 10 minutes or 25 to 30 minutes after the end of exposure. In some cases, FMD recovery was assessed every 30 minutes over a total duration of 90 minutes. FMD indicates flow‐mediated vasodilation; SHS, secondhand smoke.
Mentions: For each experiment, a single cigarette was lit, smoked for 3 minutes, and extinguished, and particle concentration in the exposure chamber was adjusted until the desired RSP starting concentration was reached (Figure 1). At that time, an individual anesthetized rat, after baseline FMD measurement, was exposed for the specified duration and was then returned to the ultrasound system for postsmoke FMD measurement. Negative controls consisted of the same duration of exposure to nonsmoky air in the exposure chamber. As in our tobacco study,34 it took roughly 10 minutes after the end of the exposure period to prepare the rat for an initial postexposure FMD measurement. For some experiments, we measured FMD again 30 minutes later to evaluate recovery.

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