This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'True regarding endothelin-1 are all except \nSelect and explain. \nA. Bronchodilatation, B. Vasoconstriction, C. Decreased GFR, D. Has inotropic effect', 'role': 'user'}, {'content': "Answer: A \nExplanation: Endothelin 1 is a broncho constrictor that it is implicated in the pathophysiology of asthma Endothelin-1, one of the most potent vasoconstrictor agents yet isolated. Endothelins cause contraction of mesangial cells which reduce GFR Endothelin-1 appears to be primarily a paracrine regulator of vascular tone. Endothelin is a positive inotropic agent in human hea Ref: Ganong's Review of Medical Physiology Twenty-Third Edition Page No:565", 'role': 'assistant'}]