What is the response of Alpha 1 receptors when stimulated?

When Alpha 1 receptors are stimulated, they primarily facilitate vasoconstriction. This is due to their location on vascular smooth muscle, where their activation leads to an increase in intracellular calcium levels, resulting in muscle contraction. This process narrows the blood vessels, thereby elevating systemic vascular resistance and increasing blood pressure.

In contrast, bronchodilation, which is associated with Beta 2 receptor stimulation, does not occur through Alpha 1 receptors. Likewise, Alpha 1 stimulation does not contribute to an increased heart rate directly; that response is mediated by Beta 1 adrenergic receptors in the heart. Therefore, the vasoconstriction resulting from Alpha 1 stimulation is critical for various physiological responses, particularly in regulating blood flow and pressure.