What neural, hormonal and local factors tend to decrease arteriole diameter? Increase?

Question

What will be an ideal response?

Answer 1

Answer: Factors that tend to cause vasoconstriction:
In terms of neural control, the sympathetic nervous system can release norepinephrine, causing vasoconstriction.
Hormones that tend to cause vasoconstriction include epinephrine (e.g. in the gut), angiotensin II, and vasopressin.
Local factors that tend to cause vasoconstriction are endothelin-1 and local high blood pressure that stretches the arteriole walls. Also high oxygen, low CO2, or high pH will tend to cause vasoconstriction.
Factors that cause tend to cause vasodilation:
Some neurons release nitric oxide, a vasodilater.
The hormones atrial natriuretic peptide and epinephrine (in skin or muscle) can be vasodilators. Note that epinephrine can be either a vasoconstrictor or dilator, depending on the tissue (the responses downstream of binding the receptor differ in these tissues).
Local factors that can induce vasodilation include low oxygen, high carbon dioxide, low pH, high K+, high osmolarity, high adenosine (these are all signatures of a highly active tissue that is not receiving sufficient blood flow), and eicosanoids, bradykinin (and other factors associated with tissue injury/inflammation). Nitric oxide can also be a local dilating factor.