Peripheral edema with antihypertensives

[Doc176]

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well I know that peripheral edema is caused by increased renin with antihypertensives.
Looking at it I know that the antihypertensives causing peripheral edema are
Alpha 2 agonists, Reserpine and Guanethidine, hydralazine ,Potassium channel openers etc
and drugs which dont cause it are
1 Beta blockers (reason as far as I know is that Beta 2 receptors increase renin release so we are actually blocking it)
2 ACE inhibitors obviously decrease aldosterone
3 Diuretics for obvious reason

Now why do Alpha 1 blockers not lead to peripheral edema despite the fact alpha 1 receptors decrease renin release when stimulated ?

Also why dont Calcium Channel blockers (the cadioselective ones) dont cause edema ?

 

[Kuvan]

Peripheral edema occurs when there's not equal vasodilation in the venous vasculature - a risk exists for leaking through the capillaries in the legs - increased risk of peripheral edema. This mechanism is the main cause for peripheral edema by dihydropyridine CCBs. That's why we don't use diuretic to treat peripheral edema caused by amlodipine, we use ACEI/ARB - which will result in a more balanced pressure gradient across the peripheral vasculature by providing vasodilation of both the arteries and veins. Even the nondihydropyridines CCBs have peripheral edema listed as one of the side effects, but it's less than dihydropyridine CCBs. Alpha-1 blockers also cause edema. It's listed as one of their side effects. However, the vasodilatory edema may be related to a few mechanisms - the one I just mentioned, stimulation of the RAAS, and the kidneys paradoxically retains sodium in an attempt to restore arterial filling. That's all I have. I'm sure you know the answer by now since the question was posted 6 years ago.