Final answer:
The α₁ Receptor is responsible for the constriction of arteriolar smooth muscle, activating a signaling pathway that increases intracellular calcium and causes muscle contraction.
Step-by-step explanation:
The receptor that mediates constriction of arteriolar smooth muscle is the α₁ Receptor. This type of receptor, upon activation, stimulates a G protein-coupled signaling pathway involving Gq, which leads to an increase in intracellular calcium levels. This cascade results in the contraction of smooth muscle fibers, thus causing vasoconstriction. The α₁ Receptor is distinctively known for this function in various blood vessels, including those in the skin, gastrointestinal system, kidney, and brain. Unlike α₁, α₂ receptors couple to Gi, reducing cAMP activity, and β receptors couple to Gs, commonly leading to smooth muscle relaxation rather than contraction.
The receptor that mediates constriction of arteriolar smooth muscle is the α₁ receptor. The α₁ receptor is an adrenergic receptor that is activated by adrenaline or noradrenaline. When the α₁ receptor is activated, it causes smooth muscle contraction, leading to constriction of arterioles.