Final answer:
Inhalation of amyl nitrite primarily causes the dilation of blood vessels due to its role as a vasodilator.
Step-by-step explanation:
Inhalation of amyl nitrite causes the dilation of blood vessels. This effect is due to amyl nitrite acting as a vasodilator, which relaxes smooth muscle cells within the vessel walls, particularly in the veins and arteries, leading to a wider lumen and decreased vascular resistance. The underlying mechanism involves the activation of nitric oxide (NO) pathways; NO is a signaling molecule that triggers vasodilation. An example of this mechanism can be seen with nitroglycerin, a medication for heart disease, which also works by releasing NO, resulting in the dilation of blood vessels and increased blood flow to the heart.
While the effects of other substances like nicotine found in tobacco smoke typically include increased heart rate, constriction of blood vessels, and raised blood pressure, the specific action of amyl nitrite contrasts with these effects by primarily causing vasodilation. It's important to note that while some drugs like epinephrine and norepinephrine can increase heart rate and constrict blood vessels, the primary impact of amyl nitrite is on the blood vessels themselves rather than directly altering heart rate.