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Results for “Marijuana Smoking”

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At least 19 recordsLinked to original sources

PubMed1992

Middle cerebral artery velocity during upright posture after marijuana smoking.

Marijuana is known to cause symptoms suggestive of orthostatic hypotension such as dizziness and fainting during upright posture. We examined changes in cerebral blood velocity (CBV) and peripheral circulation during upright posture after smoking marijuana in 10 right-handed male subjects with a previous history of exposure to marijuana. The participants were physically and mentally healthy and drug-free for a minimum of 3 months before the experiment. Middle cerebral artery CBV, blood pressure and pulse rate were recorded during reclining position and standing, before and after smoking a high-potency marijuana cigarette or a placebo cigarette administered during 2 separate visits to the laboratory. The participants were questioned about dizziness during the upright position. Six of 10 subjects reported moderate to severe dizziness during standing after marijuana but not placebo. Subjects who experienced severe dizziness during standing showed marked decreases in blood pressure and CBV. Those who reported moderate dizziness showed reduction in CBV but not blood pressure. Subjects who reported mild dizziness after marijuana and after placebo smoking showed minimal changes in blood pressure and CBV. Cerebral ischemia during upright position after marijuana smoking may be caused by hypotension and impaired cerebral autoregulation.

Adult↗

PubMed1989

Breathhold duration and response to marijuana smoke.

Marijuana smokers are frequently observed to hold the smoke in their lungs for prolonged periods (10-15 sec) apparently in the belief that prolonged breathholding intensifies the effects of the drug. The actual influence of breathhold duration on response to marijuana smoke has not been studied. The present study examined the effects of systematic manipulation of breathhold duration on the physiological, cognitive and subjective response to marijuana smoke in a group of eight regular marijuana smokers. Subjects were exposed to each of three breathhold duration conditions (0, 10 and 20 sec) on three occasions, scheduled according to a randomized block design. A controlled smoking procedure was used in which the number of puffs, puff volume and postpuff inhalation volume were held constant. Expired air carbon monoxide levels were measured before and after smoking to monitor smoke intake. Typical marijuana effects (increased heart rate, increased ratings of "high" and impaired memory performance) were observed under each of the breathhold conditions, but there was little evidence that response to marijuana was a function of breathhold duration.

Adolescent↗

PubMed1992

Regional cerebral blood flow after marijuana smoking.

Regional CBF was measured with the 133Xe inhalation technique before and thrice after smoking marijuana of two strengths and placebo in 20 physically and mentally healthy male volunteers with a previous history of exposure to marijuana. They were drug-free at the time of the study. Blood pressure, pulse rate, end-tidal carbon dioxide, end-tidal carbon monoxide, and forehead skin perfusion were quantified during the CBF measurements. Blood samples were drawn for quantification of plasma levels of delta 9-tetrahydrocannabinol (THC) before and during the 2 h after smoking marijuana or placebo. Drug-induced intoxication and changes in mood were quantified with rating scales. Marijuana smoking was associated with bilateral CBF increase, which was maximal 30 min later. Greater CBF increases were seen in the frontal region and right hemisphere. No significant CBF changes were seen after placebo. Pulse rate and respiration increased significantly after marijuana but not placebo. Both marijuana and placebo smoking were associated with increased end-tidal carbon monoxide. CBF increase in both hemispheres correlated significantly with degree of intoxication, plasma levels of THC, and pulse rate.

Adult↗

PubMed1988

A cumulative dosing procedure for administering marijuana smoke to humans.

Subjective, behavioral and physiological effects of smoked marijuana were measured with a cumulative dosing procedure which allowed dose-related effects to be determined within a single experimental session. Five male and three female occasional marijuana smokers participated. Unit doses of marijuana smoke were administered in a standardized manner on four occasions during each session, each occasion spaced 20 minutes apart. This procedure resulted in a cumulative dose of active (1.4%-THC) marijuana of 0, 2, 4 and 8 puffs after the four successive smoking occasions, respectively. Dependent variables were measured after each smoking occasion. Smoke absorption was monitored by measuring expired air carbon monoxide levels. Subjects participated in three identical sessions spaced a week apart in order to assess the reliability of the procedure. During a fourth session, only placebo (0.0%-THC) marijuana was administered throughout the session as a control. Significant linear dose-effect functions were obtained on several measures, with good session-to-session replicability of most effects. The results demonstrate the feasibility of using a cumulative dosing procedure to evaluate dose-related effects of smoked marijuana in humans. The procedure would be especially useful for the assessment of shifts in dose-effect curves as a result of various experimental manipulations.

Adolescent↗

PubMed1990

Smoked marijuana effects on tobacco cigarette smoking behavior.

The effects of marijuana smoke exposure on several measures of tobacco cigarette smoking behavior were examined. Eight healthy adult male volunteers, who smoked both tobacco and marijuana cigarettes, participated in residential studies, lasting 10 to 15 days, designed to measure the effects of marijuana smoke exposure on a range of behavioral variables. Tobacco cigarettes were available throughout the day (9:00 A.M. until midnight). Each day was divided into a private period (9:00 A.M. to 5:00 P.M.), during which subjects were socially isolated, and a social period (5:00 P.M. to midnight), during which subjects could interact. Under blind conditions, subjects smoked placebo and active marijuana cigarettes (0%, 1.3%, 2.3%, or 2.7% delta 9-tetrahydrocannabinol) four times daily (9:45 A.M., 1:30 P.M., 5:00 P.M. and 8:30 P.M.). Each subject was exposed to both placebo and one active dose over 2- to 5-consecutive-day intervals, and dose conditions (i.e., placebo or active) alternated throughout the study. Active marijuana smoking significantly decreased the number of daily tobacco smoking bouts, increased inter-bout intervals and decreased inter-puff intervals. Marijuana decreased the number of tobacco smoking bouts by delaying the initiation of tobacco cigarette smoking immediately after marijuana smoking, whereas decreases in inter-puff intervals were unrelated to the time of marijuana smoking. No consistent interactions between marijuana effects and social or private periods (i.e., time of day) were observed.

Adult↗

PubMed1989

The regularity of smoked marijuana self-administration.

Three male research volunteers lived in a residential laboratory for 12 days in a study designed to investigate factors controlling patterns of marijuana smoking. All contact with the experimenters was through a networked computer system and subjects' behaviors were continuously recorded. During the first six hr of the day (0945-1545), subjects remained in their private rooms engaging in planned work activities, and during the remainder of the day (7 3/4 hr) they were allowed to socialize (1600-2345). Subjects were instructed that up to five active marijuana cigarettes (1.84% delta 9 w/w THC) could be smoked on designated days between 0945 and 2200. Cigarettes were available on request. Subjects requested all five cigarettes on 15 of 18 possible occasions (three subjects x six days of availability) with a mean latency to the first cigarette of 22 min. The pattern of self-administration was remarkably similar among subjects with all subjects smoking two cigarettes during the private work period and three cigarettes during the social access period. Subjects 1 and 2 smoked 90% of their social period cigarettes together in the social area, while Subject 3 smoked all of his cigarettes alone in his private room.

Adult↗

PubMed1977

Effect of marijuana and placebo-marijuana smoking on psychological state and on psychophysiological cardiovascular functioning in anginal patients.

Ten male anginal patients with angiographically documented coronary artery disease, in a randomized double-blind crossover study, smoked one marijuana cigarette (containing 18 mg of delta-9-THC) on one morning and one placebo marijuana cigarette (containing 0.05 mg of delta-9-THC) on a successive morning. Significant increases occurred in average cognitive and intellectual impairment scores, derived from the objective content analysis of 5 min of speech, 30 mins after smoking the marijuana cigarette as compared to the placebo marijuana cigarette, and these scores decreased to near presmoking levels 60 min after smoking. No significant average changes occurred in anxiety or three hostility scale scores following smoking marijuana. Sizable individual differences were noted in the psychological responses to marijuana smoking due, presumably, to personality differences and/or differences in THC pharmacokinetics. Significant psychocardiovascular hemodynamic correlations, as measured by echocardiography, were observed during placebo-marijuana smoking between hostility inward scores and systolic blood pressure and ejection fraction, overt hostility outward scores and diastolic blood pressure, as well as between anxiety scores and stroke volume and left ventricular end-diastolic dimension and left ventricular diastolic volume. These significant psychophysiologic correlations were all eliminated during marijuana smoking. In view of associated findings that marijuana smoking decreased myocardial oxygen delivery, decreased exercise time until the onset of anginal pain, and increased myocardial oxygen demand in anginal patients, the use of marijuana by such patients is clearly inadvisable.

Adult↗

PubMed1976

Marijuana smoking and cold tolerance in man.

Ten men who were marijuana users served as subjects in a study of the effects of marijuana smoking on response to cold. Cold water (28 degrees C for 60 min) and cold air (20 degrees C for 120 min) mediums were utilized with three exposures in each medium. The three exposures followed smoking marijuana, smoking placebo, and a no-smoking control period. Additionally, a breathhold experiment preceded and followed the four smoking periods. Marijuana and placebo smoke were inhaled from a spirometer with each man receiving the smoke of 0.739 g of marijuana and placebo. Smoking marijuana did not greatly modify body heat content, since rectal temperature and most peripheral temperatures were not altered. However, temperatures over voluntary muscles likely to be involved in shivering were elevated. Heat production also greatly increased after marijuana, suggesting that it had stimulated shivering. Marijuana also produced tachycardia and abolished apneic bradycardia. The mechanism of this action is not clear, but some sympathetic involvement is indicated.

Adaptation, Physiological↗

PubMed1985

'Hangover' effects the morning after marijuana smoking.

Thirteen male marijuana smokers participated in a study to determine whether marijuana smoked in the evening would result in measurable subjective or other behavioral effects the following morning. Subjects smoked either active (2.9% delta 9THC) or placebo (0.0% delta 9THC) marijuana cigarettes according to a standardized smoking regimen. Smoke inhalation was monitored by measuring expired air carbon monoxide (CO) levels before and after smoking. Acutely, active marijuana produced significant changes in heart rate, CO level, various measures of subjective effects, and behavioral tasks of card sorting, free recall and time production. When the test battery was repeated the following morning (approx. 9 h after smoking), significant changes were observed on two subjective effects scales and on the time production task after active, but not placebo, marijuana. These apparent 'hangover' effects were different from the acute effects of marijuana. The findings suggest that marijuana smoking can produce residual (hangover) effects the day after smoking. The precise nature and extent of these effects, as well as their practical implications, remain to be determined.

Adult↗

PubMed1987

The effect of subacute marijuana smoke inhalation on experimentally induced dermonecrosis by S. aureus infection.

Dermonecrosis was induced in ICR mice by subcutaneous implantation of Staphylococcus aureus absorbed onto sterile cotton pellets. This model was used to assess the effects of marijuana smoke, marijuana placebo smoke and delta 9-tetrahydrocannabinol (delta 9-THC) on the local immune response to bacterial infection. Mice were exposed to 40 or 80 "puffs" of marijuana smoke, marijuana placebo smoke or air daily for 4 consecutive days. The estimated dose of delta 9THC per day generated from 40 or 80 puffs of marijuana smoke was 3.2 and 6.4 mg/kg, respectively. A group of sentinel (Shelf) control mice were included in each experiment. The necrotic index (NI) of mice exposed to 40 or 80 puffs of marijuana smoke were 67% and 44% of control, respectively. Air exposed mice showed a necrotic index comparable to the shelf control group. In chronically (60 days) exposed mice (80 puffs per day) the necrotic index was about 12% of control, while air-exposed mice were about 40% of control. Placebo marijuana smoke exposed mice had a NI comparable to that of marijuana smoke exposed mice which suggested that the reduction in NI was unrelated to the pychomimetic component delta 9THC. To further explore which of the constituents of marijuana were responsible for the decreased NI, the ethanol extract from marijuana leaves was partioned between water (cannabinoid free) and chloroform (cannabinoid rich). Injection of the cannabinoid free fraction produced comparable decrease in the NI as observed with whole marijuana smoke, while the cannabinoid rich fraction produced no effect. delta 9THC at a dose of 10 mg/kg per day did not alter the NI.

Animals↗

PubMed1992

No increase in carcinogen-DNA adducts in the lungs of monkeys exposed chronically to marijuana smoke.

Rhesus monkeys exposed to marijuana smoke either 7 or 2 days/weeks (HI and LO groups, respectively), or ethanol-extracted marijuana smoke for 7 days/week (EM) or sham treatment (SH) for 1 year were sacrificed 7 months following the last exposure. Pulmonary levels of carcinogen-DNA adducts were determined. Although mean or median adduct levels were not statistically different, 15 of 22 adduct measures were highest in the EM group and lowest 12 of 22 times in the SH group. The levels of aromatic carcinogen-DNA adducts seem no higher in the lungs of animals exposed to marijuana smoke than in untreated animals. Ethanol-extracted marijuana may have effects greater than marijuana itself.

Animals↗

PubMed1990

Marijuana smoking and carcinoma of the tongue. Is there an association?

There is considerable theoretical evidence that marijuana should be carcinogenic. However, most reviews have found no direct evidence of chronic marijuana smoking causing lung cancer. Some recent reports implicate marijuana smoking as a cause of cancer of the upper aerodigestive tract, though most of the subjects were exposed to other, possibly confounding, etiologic factors, namely tobacco and alcohol. We report two cases of squamous cell carcinoma of the tongue in men who chronically smoked marijuana but had no other risk factors. The totality of cases may point to a predilection of marijuana smoke for carcinogenesis in the upper aerodigestive tract. This correlates with nonmalignant effects and may be related to a different method of smoking marijuana compared with tobacco.

Adult↗

PubMed1976

Intact humoral and cell-mediated immunity in chronic marijuana smoking.

The immune system of 12 healthy chronic marijuana-smoking adults was evaluated while they smoked marijuana daily for 64 consecutive days under controlled hospitalized conditions. Studies included enumeration of B and T cell subpopulations, lymphocyte proliferative responses to PHA and to allogeneic cells, and serum immunoglobulin levels. Percent B cells, initially low in 2 patients, became normal. Baseline total B cells, determined either by surface immunoglobulins (338 cells/mm3 +/- 60 SEM) or complement receptors (162 cells/mms +/- 27) were significantly (p less than 0.05) less than control but increased to normal (485 +/- 97 and 239 +/- 47) over time. Percent T cells, initially low (less than 40%) in 4 patients, became normal. Baseline T cells (951 cells/mm3 +/- 70 SEM), significantly lower than controls (2,010 +/- 210, p less than 0.05), increased to normal by day 63 (1,875 +/- 281). In vitro lymphocyte response to graded doses of PHA and to allogeneic cells was normal initially and did not change over time. Serum IgG (1,064 +/- 33), IgA (166 +/- 13), and IgM (96 +/- 6) were normal. Serum IgE levels increased in 4 subjects without evidence of allergy. Short-term chronic marijuana use does not have a substantial adverse effect on B or T cells of young healthy adults.

Adult↗

PubMed1991

Effects of single and repeated marijuana smoke exposure on fetal EEG.

The effect of single and repeated marijuana smoke exposure on fetal EEG was investigated in the chronic fetal lamb model using power spectral analysis. Maternal inhalation of marijuana smoke (n = 9) resulted in a significant reduction in total power and power distribution in the delta (1-4 Hz) band, and an increase in power distribution in the faster frequencies in the first h after smoke inhalation. These EEG changes were not observed following maternal inhalation of placebo smoke (n = 5), nor in animals with 3-5 prior exposures to marijuana smoke (n = 5). These results suggest that the effects of marijuana smoke exposure on fetal EEG is short-lived and tolerance develops rapidly with repeated exposure.

Animals↗

PubMed1988

Ovine placental perfusion balance: effect of marijuana smoke.

This study was designed to test the hypothesis that maternal marijuana smoking impairs placental oxygen transfer in late ovine pregnancy by disrupting perfusion balance between the maternal and fetal placental circulations. Placental hemodynamics were assessed in nine chronically prepared ewes 1 hour after exposure to smoke from either a marijuana (n = 5) or a placebo (n = 4) cigarette. When compared with placebo smoke, maternal marijuana smoke exposure resulted in a fall in both uterine and umbilical placental vascular resistance and a 30% improvement in placental perfusion balance at a cotyledonary level. We conclude that maternal marijuana smoking in late ovine pregnancy has a direct relaxant effect on both maternal and fetal placental vascular smooth muscles that decreases the normal heterogeneity of flow and improves macroscopic placental perfusion balance. However, the observed concurrent 6 torr decrease in fetal oxygen tension suggests that perfusion balance is actually disrupted at a microcirculatory level.

Animals↗

PubMed1977

High-pressure liquid chromatographic--mass spectrometric determination of delta9-tetrahydrocannabinol in human plasma following marijuana smoking.

A method was developed for analyzing delta9-tetrahydrocannabinol (I), a psychotomimetic constituent found in marijuana smoke. The developed method utilizes a high-pressure liquid chromatographic (HPLC) gradient elution program to separate I from the other major cannabinoids in marijuana smoke. To achieve the sensitivity required to detect I in human plasma following marijuana smoking, a mass spectrometric quantification method was developed to analyze the HPLC eluant. To 1 ml of human plasma was added a known amount of internal standard, trideuterated I. This stable isotope provided a check on extraction efficiency, a marker for UV monitoring of the HPLC effluent and subsequent collection, and a convenient mass for mass spectrometric quantification. An ion-counting technique was used in conjunction with the peak matching accessory of the mass spectrometer to provide for a rapid comparison between molecular ions of I and the internal standard. The method was linear, accurate, and reproducible over the concentration range expected for I in plasma following marijuana smoking; 2.5 ng/ml was the lower practical limit of detection. Plasma from 11 male subjects was analyzed by the method at appropriate intervals up to 24 hr after the smoking of a marijuana cigarette containing 10.8 mg of I. Results demonstrated that levels of I could be determined accurately in the plasma of marijuana smokers in the 1-hr period following smoking.

Adult↗

PubMed1988

A marijuana smoking cessation clinical trial utilizing THC-free marijuana, aversion therapy, and self-management counseling.

Twenty-two volunteer adult chronic marijuana smokers participated in a smoking cessation clinical trial. The mean age of the 16 male and 6 female subjects was 29.8 years. The mean number of years of marijuana smoking was 13.7. The mean number of daily marijuana cigarettes smoked was 3.4. The clinical trial consisted of five consecutive days of 50 minute aversion therapy sessions (faradic, rapid smoking, and quick puffing) utilizing THC-free marijuana. Three weekly 60 minute group cohort sessions in self-management counseling followed. The treatment period spanned four weeks. Pretreatment and posttreatment (one month interval) the Shipley Institute of Living Scale was administered to measure changes in both cognitive functioning and organic brain dysfunction. All 22 subjects achieved abstinence (by self-report) by the end of the five days of aversion therapy; 19 of 21 subjects (90.5%) reported abstinence at the conclusion of the clinical trial, following the group sessions. At six months post treatment follow-up 15 of the 20 subjects (75.0%) reported abstinence; at 12 month posttreatment follow-up 16 of the 19 subjects (84.2%) achieved abstinence. The mean number of daily marijuana cigarettes smoked by the subjects decreased from a baseline pretreatment level of 3.40 to 0 at the conclusion of aversion therapy, .07 at the conclusion of the clinical trial, .26 at six month posttreatment follow-up and .23 at the 12 month posttreatment follow-up. The mean scores on the Shipley Institute of Living Scale, were: IQ 106 and CQ 92 at pretreatment; IQ 112 and CQ 104 at posttreatment. The difference in these means was significant for both intelligence and conceptual quotient. The investigators conclude that the treatment procedure offers promise as a marijuana smoking cessation treatment program.

Adult↗

PubMed1989

The effect of marijuana smoke exposure on murine sarcoma 180 survival in Fisher rats.

Fisher rats were treated for 28 or 60 days to multiple exposures to the smoke of marijuana or marijuana placebo cigarettes. Primary, secondary and in some instances tertiary tumor implants were performed. Murine sarcoma 180 tumor cells (7.5 x 10(7)) were implanted subcutaneously on day 1, 14 and 28 following initiation of smoke exposure (28 day studies) or on day 1, 14 after cessation of smoke exposure (60 day studies). Tumor areas were measured on alternate days beginning on the second or third day after implantation for 13 or 14 days. Exposure to both marijuana and placebo smoke for 28 days (6, 9 and 18 cigarettes per day) resulted in suppressed growth of secondary and tertiary implants. Administration of delta 9 tetrahydrocannabinol (50 mg/kg, i.p., 20 days) failed to suppress the growth of primary and secondary tumors. This suggests that noncannabinoid constituents of the smoke may contribute to the suppression of tumor growth. Exposure of rats to 9, but not 4 or 6, marijuana or placebo cigarettes per day for 60 days suppressed the growth of primary but not secondary tumors. Thus, the effects of smoke exposure appear to be lost by two weeks after cessation of treatment. The possible existence of a non-cannabinoid immunostimulant in the smoke is discussed.

Animals↗