Receptors of hemodynamics

Q: Blood vessels contain which of the receptors?

A) Beta-1
B) Beta-2


Answer: B

To understand the mechanism of hemodynamics, it is essential to know the main categories of receptors, their location, and their function. Most of these receptors are known for more than seven decades but still eludes clinicians at the bedside.

Alpha-1 adrenergic receptors are located in vascular walls and induce significant vasoconstriction. 

Beta-1 adrenergic receptors are mostly present in the heart and increase inotropic and chronotropic effects but minimal vasoconstriction. 

Beta-2 adrenergic receptors are present in blood vessels and induce vasodilation. 

Dopamine receptors are present in the renal, splanchnic (mesenteric), coronary, and cerebral vascular beds; stimulation of these receptors leads to vasodilation. A subtype of dopamine receptors causes vasoconstriction by inducing norepinephrine release. 

Calcium sensitizers: These agents increase the sensitivity of the myocardial contractile apparatus to calcium, causing increase myocardial contractility (eg, pimobendan, levosimendan). A subtype of calcium sensitizers is phosphodiesterase inhibitors, which increase inotropy along with vasodilation 

Angiotensin II is a vasoconstrictor that is part of the renin-aldosterone-angiotensin (RAAS) system. Stimulation of these receptors increases cytosolic calcium concentration and mediate vasoconstrictive effects as well as aldosterone and vasopressin secretion.


#hemodynamics


References:

1. AHLQUIST RP. A study of the adrenotropic receptors. Am J Physiol 1948; 153:586. 

2. Müllner M, Urbanek B, Havel C, et al. Vasopressors for shock. Cochrane Database Syst Rev 2004; :CD003709. 

3. Catt KJ, Mendelsohn FA, Millan MA, Aguilera G. The role of angiotensin II receptors in vascular regulation. J Cardiovasc Pharmacol 1984; 6 Suppl 4:S575.