Posted by Amigan on April 4, 2008, at 0:39:51
In reply to Re: High BP on Selegiline! B-Blockers, good?, posted by undopaminergic on April 3, 2008, at 22:04:23
> >
> > > Probably a beta blocker would be the best drug to try to prevent the increase in blood pressure due to norepinephrine.
> >
> > how sure are you about this? From what i have read, beta blockers can have exactly the opposite results in the present of a sympathomimetic factor and perhaps in cases of excessive NE, too.
> > The Beta receptors in blood vessels are responsible for vasodilation, while the Alpha receptors for vasoconstriction. THUS, if you block the B receptors, while the Alpha ones remain stimulated by the excessive N,NE or the SM factor, you have an increase in blood pressure.
> >
>
> Beta2-adrenoceptors mediate many of the (usually) desirable effects of adrenaline - including vasodilation, bronchodilation, and reduction of allergic responses, although they also increase heart rate, and their improvement of muscular blood flow may have undesirable side-effects (e.g. tremor). Selective beta1-adrenergic antagonists ("cardioselective" beta-blockers) should leave the beta2-receptors alone, but their primary effect is to reduce heart rate, which will reduce blood pressure, but not reverse the effects of vasoconstriction caused by selegiline-induced noradrenaline release (assuming that is the cause of your elevated BP).No. We are not talking about adrenoreceptors. I'm talking about ordinary, post-synaptic antagonism of the B adrenergic receptor (the standard pharmacological action of all B-Blockers)
Blockage of these receptors in the heart, does lead to decreased heart rate and output, but in the small blood vessels, COULD lead to vasoconstriction, (increased BP) especially in the presence of sympathomimetic drugs for the reasons which i have already explained in my previous post.
poster:Amigan
thread:819397
URL: http://www.dr-bob.org/babble/20080330/msgs/821489.html