Vascular Physiology

1. Effects of Cortisol on Blood Vessels:

Cortisol and aldosterone are both metabolic products of cholesterol and share similar properties. Cortisol increases in response to adrenergic receptors stimulated by catecholamines, leading to an increase in vascular smooth muscle tone. This contributes to:

• Increased blood pressure: Due to vasoconstriction, increasing peripheral resistance.

• Decreased blood flow: Due to narrowed blood vessels.

• Increased sodium and water excretion: Cortisol also plays a role in regulating water and electrolyte balance, which can indirectly affect blood flow.

2. Vascular Response to Decreased Blood Flow:

When blood flow decreases, the body has two response mechanisms:

• Intrinsic (local) mechanism: Local oxygen deficiency stimulates the release of chemical mediators, leading to vasodilation and increased blood supply to vital organs like the heart, brain, and kidneys.

• Extrinsic mechanism: Receptors in the aortic arch and carotid sinus detect decreased blood flow, triggering a reflex vasoconstriction and increasing blood pressure.

3. Stress Test with Vasodilators in Atherosclerosis:

• Coronary atherosclerosis leads to narrowing and blockage of blood vessels, reducing blood flow. Therefore, the body has maximally activated its vasodilatory capacity to maintain blood flow.

• Using vasodilators in this case will not further dilate the coronary arteries (as they are already maximally dilated), but will dilate the surrounding blood vessels.

• This leads to increased blood flow and oxygen delivery to the surrounding vessels, exacerbating the oxygen deficiency of the coronary arteries, leading to a risk of angina or myocardial infarction.

4. Note:

• The information above is for reference only and does not substitute for the advice of a medical professional.

• The use of vasodilators in atherosclerosis should be prescribed and closely monitored by a specialist.