Flashcards in Alpha Blockers Deck (18)
Alpha adrenergic receptors are mainly active where?
two types of alpha receptors are?
Alpha one and alpha two
Alpha one is where and does what?
Post-synaptic. Leads to increased intracellular Calcium by increasing the production of DAG (diacylglycerol) and IP3. Smooth muscle contraction. 1b and 1d in the vasculature, 1a in the prostate.
pre-synaptic, activation leads leads to decreased production of cyclic AMP and inhibits norepinephrine feedback so it keeps getting released.
What effect does an alpha blocker have on norepinephrine?
Severely lessens its effects on blood pressure. Bp does not go up.
Beta blocker on norep?
Alpha blocker on epinephrine?
Epinephrine is weird. It activates alpha receptors and beta receptors. Activation of alpha receptors obviously causes a vaso constrictive effect which raises blood pressure. Activation of Beta 2 receptors is the opposite. It creates a vasodilatory effect. SO alpha blockers block the alpha receptors but leave the beta blockers open and lead to a decrease in blood pressure because the only thing that works is the vasodialator.
Beta blockers allow epinephrine to inc blood pressure
Alpha blockers on isoproterenol
No effect on alpha receptors so alpha blockers. Beta receptors are the only things it effects so blood pressure still decreases dramatically. Beta blockers on the other hand will keep isoproterenol from decreasing BP.
Phenotolamine has an affinity for which receptors
Both alpha one and two
phenoxybenzamine has affinity for which
alpha one more than two
Terazosin, Doxazosin, Prazosin have affinity for which receptors?
Alpha one way more than 2
What can blocking alpha 1a lead to?
improving urine flow rate in BPH patients.
toxicity of the alpha blockers
orthostatic hypotension on first dose, tachycardia with blockade of alpha 2-presynaptic receptors
alpha 1 and 2 antagonist.
sinus tach, bnasal decongestion, etc...
Low doses of phentolamine do what and how?
raise BP be selectively blocking the alpha 2 receptor
High doses of phentolamine do what?
Lower BP by selectively blocking the alpha one receptor.