Advanced Dental Admission Test (ADAT)

What additional effect do Beta 1 adrenergic receptors have aside from increasing heart rate?

1. Increased vasodilation

2. Enhanced renin release from the kidney

3. Vasoconstriction in systemic circulation

4. Decreased blood sugar levels

The correct answer is: Enhanced renin release from the kidney

Beta 1 adrenergic receptors primarily influence cardiac function, notably by increasing heart rate and contractility. In addition to these cardiac effects, stimulation of Beta 1 receptors also leads to an important physiological response in the kidneys: the enhancement of renin release. Renin is an enzyme that plays a critical role in the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure and fluid balance in the body. When Beta 1 receptors are activated, particularly in the juxtaglomerular cells of the kidneys, there is an increase in renin secretion. This leads to a cascade of events that result in elevated levels of angiotensin II, which ultimately causes vasoconstriction and increases blood pressure, as well as stimulating the adrenal glands to release aldosterone and regulate sodium and water retention. The other options do not reflect additional effects associate with Beta 1 receptor activation. For instance, vasodilation is more closely associated with Beta 2 receptors. Vasoconstriction in systemic circulation is typically a result of activation of Alpha adrenergic receptors, while lowered blood sugar levels are not a direct result of Beta 1 receptor activity. Thus, enhancing renin release is a vital additional effect of Beta