What is parasympathetic withdrawal and how does it relate to the compounds you mentioned above? Wouldn't Clenbuterol cause low blood pressure given the fact that it is a vaso-dilator?
Your blood vessels during rest (Diastole) are under control of the parasympathetic nervous system, this system is responsible for lowering the resting heart rate, and controlling the tonus of the smooth muscles surrounding our blood vessels.
Since blood pressure is: Stroke volume x Peripheral resistance x heart rate, or cardiac output x peripheral resistance, affecting one of the variables will increase blood pressure.
Ephedrine is a adrenergic agonist, which means it will bind to the receptors of the sympathetic nervous system which will always override parasympathetic action. Parasympathetic tone is active during rest and digest, and sympathetic is the active system..
Without parasympathetic tone, the intrinsic heart rate would be 100 beats per minute (roughly). If you use ephedrine, the parasympathetic system is overridden by the adrenergic agonist (Adrenal receptors respond to epinephrine/norepinephrine).
While clen does cause some degree of vaso-dilation, it is a beta-2 agonist, and will bind to the tissue in the heart, and the alveoli in the lungs. It will raise the heart rate, and the ejection volume (stroke volume) so it will likely cause an increase in systolic blood pressure, but most likely a drop in diastolic blood pressure.
This is a lot of convoluted information, but essentially, these supplements bind to receptors that are there as a physiological control switch, and cause a deviation in resting values.
In essence, I would guess that ephedrine would raise both diastolic and systolic blood pressure, and thus a noticeable increase in mean arterial pressure. Clen, I don't know, I would have to test the mean arterial pressure, but would still guess it would increase it.
Be safe bro's, and I wrote this real fast. I will look back later to make sure it is clear enough to understand.