Neurally Mediated Hypotension???

Glen M. Sizemore gmsizemore2 at yahoo.com
Fri Feb 1 10:07:29 EST 2002


Mat: Well it depends what you mean by 'neural'... Blood pressure is
controlled by various systems, for example local metabolite concentrations
in tissues and blood vessels, Starling mechanisms in the heart itself and a
more global regulatory mechanism from various brain centres e.g.
sympathetic/parasympathetic efferents to the heart and neuroendocrine axes.
However if you mean by 'neurally mediated' whether blood pressure is to some
extent unde conscious control then I don't know. You can manipulate the
mechanisms that control blood pressure, e.g. if you hold your breath your
heart rate falls, but as to just thinking 'lower blood pressure' and it
happening I doubt it! Of course certain states of mind such as stress do
affect BP, but again via the 'unconscious' mechanisms.



GS: It isn't a matter of "conscious vs. unconscious" (see, for example, the
classic experiments demonstrating operant conditioning of minute movements
of striated muscles - without awareness) but, rather, one of the "direct
operant conditionability" of smooth muscle responses. To my knowledge, the
operant conditioning of smooth muscle (in curarized animals) has never been
successful. A student of Neil Miller's claimed to have done it, but this was
exposed as a fraud and the student committed suicide. Smooth muscle
responses can be produced via operant conditioning (this is the essence of
biofeedback) but, apparently, only because the striated muscle is involved.

Glen



"mat" <mats_trash at hotmail.com> wrote in message
news:43525ce3.0202010439.550e71e2 at posting.google.com...
> "Richard Price" <explore65 at yahoo.com> wrote in message
news:<RSi68.11201$By6.1234040 at newsread2.prod.itd.earthlink.net>...
> > Hello  -
> >
> > I am embarking on a quest to research this topic. I hope to find out
what
> > the medical establishment thinks of it, and in particular the
neurologists
> > gut reaction to the proposition(s). Maybe the "syndrome"(? not medically
> > versed here) has been proven already, but from what I've read so far(a
John
> > Hopkins reports from 5 years ago), it is seems to be more of a
hypothesis
> > still.
> >
> > So, any feed back would be appreciated. Sources of information. Thoughts
on
> > the subject. References to research groups or individuals.
> >
> > Best regards
> > Richard
>
> Well it depends what you mean by 'neural'... Blood pressure is
> controlled by various systems, for example local metabolite
> concentrations in tissues and blood vessels, Starling mechanisms in
> the heart itself and a more global regulatory mechanism from various
> brain centres e.g. sympathetic/parasympathetic efferents to the heart
> and neuroendocrine axes.  However if you mean by 'neurally mediated'
> whether blood pressure is to some extent unde conscious control then I
> don't know.  You can manipulate the mechanisms that control blood
> pressure, e.g. if you hold your breath your heart rate falls, but as
> to just thinking 'lower blood pressure' and it happening I doubt it!
> Of course certain states of mind such as stress do affect BP, but
> again via the 'unconscious' mechanisms.





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