Complex sentence: In the coronary circulation, norepinephrine elicits vasoconstriction, due to the predominance of beta-adrenergic receptors in the coronary circulation, however metabolic control factors will increase as a result of increased oxygen demand in the heart and will more greatly influence vasodilation.
Split into simpler sentences: In the coronary circulation, however, norepinephrine vasoconstriction, due to the predominance of beta-adrenergic receptors in the coronary circulation. However, metabolic control factors will increase as a result of increased oxygen demand in the heart and will more greatly influence vasodilation.