From: [p--r--n] at [gsb013.cs.ualberta.ca] (Peter Jordan)
Newsgroups: talk.politics.misc,talk.politics.drugs,sci.med,rec.drugs.cannabis
Subject: Nicotine and THC and your heart. WAS Re: Legalize rape today!
Date: 9 Sep 1995 08:09:11 GMT

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Cardiovascular Effects
	Although many toxic chemicals have been identified in cigarette smoke,
carbon monoxide and nicotine appear to be the major offenders, with the former
receiving increasing attention.  These substances increase the cardiac work
load while decreasing the oxygen supply and simultaneously disrupting the
integrity of the peripheral vascular system.  NICOTINE increases heart rate and
blood pressure and enhances platelet aggregation and peripheral lipid
mobilization by stimulating catecholamine release.  The increase in pulse
and blood pressure is evident following low- or high-nicotine cigarettes, but
not following non-nicotine cigarettes(Arnow et al., 1974, p. 330).  Nicotine
also reduces the HDL/LDL ratio (Hurst, 1981).  Whereas low tar and nicotine
cigarettes can be produced, or the substances filtered from higher tar and
nicotine cigarettes, carbon monoxide cannot be filtered from cigarettes.  The
increased bonding of COHb over oxygen shifts the oxyhemoglobin dissociation
curve to the left.  The mild hypoxia decreases available oxygen to the
myocardium, stimulates polycythemia, and damages arterial lining, accelerating
atherogenesis and platelet aggregation, especially in the presence of
hyperlipidemia.  Hematocrit levels of blood donors who smoke is higher than
nonsmoking donors, with significantly high RBC volume and reduced plasma
volume.  Smokers who quit or markedly reduce smoking demonstrate a return to
normal levels (Smith and Landaw, 1978).
Topping et al. (1977) are studying smokers' predisposition to peripheral
vascular disease, which closely resembles type III hyperlipoproteinemia.
Occlusive peripheral vascular disease is further irritated by the
vasoconstriction resulting from increased catecholamine levels.

Nursing Implications
	All of these factors indicate the grave consequences that cigarette
smoking (particularly nicotine and carbon monoxide) has on the
cardiovascular system.  It is time that health care professionals take a
stronger stand on smoking. . . . 
Additional research is needed to identify the factors which stimulate
initial smoking and promote continued smoking, as the knowledge of the
hazards of smoking does not decrease the incidence. . . .
An individual concerned with health compromises his professional credibility
if he elects to take a supportive or even neutral stand on smoking.

Marijuana

	The topic of smoking is not complete without a discussion of marijuana.
It is unlikely that use of this substance is a passing fad, and it seems
equally unlikely that legal prohibition of its use will be completely
succesful.  Therefore, it is imperative that full knowledge of the effects of
marijuana be pursued so that individuals can make an informed choice about
its use.
	In addition to the presence of delta 9 tetrahydrocannabinol (THC),
the active substance in marijuana, marijuana also contains carbon particles,
carbon monoxide, and other sometimes unknown, substances in varying amounts.
Discounting for the moment the effects of those other chemicals which may find
their way into marijuana, what physiologic effects of cannabis on the
cardiovascular msystem have been identified ?
Because cannabis use is rarely equal to the average consumption of cigarettes
we will discount the effects of carbon monoxide.
	Kanakis and Rosen (1977) acknowledged the variability which
may enter studies if the factors of dose and tolerance are not controlled.
Although they recommended further study, they reported that sinus
tachycardia occured when subjects smoked marijuana, with sinus bradycardia
occuring at levels of intoxication.  Improved function of the sinus node,
with facilitation of AV nodal conduction, and small, but significant,
increase in systolic and diastolic blood pressures have been observed.
Also, increased cardiac output, with and without increased stroke volume,
increased ejection fraction, and increased left ventricular ejection time
have been reported.  Toskin et al. (1977) concluded from a study of 21
experienced, healthy subjects that although heart rate rose from 16-53%
following 1-3 marijuana cigarettes, no other significant effect was
demonstrated when heart rate was accounted for.  Thus, it was felt, left
ventricular function was not affected favourably or unfavourably.
Prakosh et al.(1975) reported that their subjects, after smoking
three-quarters of one marijuana cigarette, also demonstrated an increase in
heart rate and BP but a decrease in end-diastolic volume, stroke index,
and ejection fraction.
The subjects who smoked placebo marijuana experienced a decreased
end-diastolic volume, stroke index, cardiac index and ejection fraction.
However, the decrease in stroke index and ejection fraction was greater and
longer lasting from the marijuana than from the marijuana than from the
placebo.  Benowitz and Jones (1977), in a study of combined effect of
marijuana with one of four drugs, found no effect with isoproterenol or
phenylephrine, but found significant elevation
of BP and heart rate when THC and atropine were administered.
Propranolol's ability to slow heart rate was less pronounced during THC
administration.  It seems premature to draw conclusions.  Results of stress
tests and cannabis and other pharmacologic interactions would expand current
knowledge.  Certainly, the element of emotional stress cannot be ignored.
Perhaps, low-level cannabis use may produce the indirect benefit of relief
of tension.  However, potential risk of cannabis or, perhaps, risk to selected
populations can not be disregarded.  If cannabis prescription is approved 
for use in some medical conditions, it will be necessary to conduct research
on the effects of its use on the cardiovascular system in patients with
and without known cardiovascular disease.

Coffee and Caffeine

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Source: Cardiovascular Nursing; Mary A. Reuther, Carla B. Hansen; Medical
Examination Publishing Co.; 1985.

>This is true.

Peter Jordan (I can go on and on and on with other books if you like.)
-- 
http://ugweb.cs.ualberta.ca/~pjordan/