Which effect is produced by norepinephrine?

Norepinephrine, as a key neurotransmitter and hormone, primarily exerts its effects through the activation of alpha-adrenergic receptors, which leads to vasoconstriction in many vascular beds. This mechanism is responsible for its role in increasing systemic vascular resistance. Consequently, with the increase in vascular resistance, there is a notable rise in blood pressure. This response is particularly critical during stress or 'fight or flight' situations, as it helps to ensure that vital organs receive adequate blood flow and oxygen supply.

In contrast, the other options reflect effects that are not typically associated with norepinephrine. For example, vasodilation of renal arteries and reduced systemic vascular resistance suggest a lowering of blood pressure, which is opposite to what norepinephrine achieves. Balancing renal function may involve various hormones and factors, but norepinephrine specifically is not primarily involved in this regulatory process in the same direct manner.