Which of the following has vasodilator effect.. nicotine

Which of the following has vasodilator effect?

• a- nicotine
• b- cholestyramine
• c- urokinase
• d-vit. A

The correct answer is (a) nicotine.

Nicotine is a stimulant that binds to nicotine acetylcholine receptors (nAChRs) in the sympathetic nervous system. This binding triggers a cascade of events that leads to the release of norepinephrine (noradrenaline) and epinephrine (adrenaline) from the adrenal glands. These hormones cause blood vessels to dilate, leading to a temporary increase in blood pressure.

The other options do not have a vasodilator effect:

- Cholestyramine:

is a bile acid sequestrant, which means that it binds to bile acids in the digestive tract and prevents them from being absorbed into the bloodstream. This can help to lower cholesterol levels. However, cholestyramine does not affect blood vessel dilation.

- Urokinase:

is an enzyme that is used to dissolve blood clots. It does not have a direct effect on blood vessel dilation.

- Vitamin A:

is a fat-soluble vitamin that is important for vision, reproduction, and immune function. It does not have a direct effect on blood vessel dilation.

Therefore, the only option that has a vasodilator effect is nicotine.