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Chapter 17: Vasoactive Peptides

Field workers exposed to a plant toxin develop painful fluid-filled blisters. Analysis of the blister fluid reveals high concentrations of a peptide. Which of the following is a peptide that causes increased capillary permeability and edema?

(A) Angiotensin II

(B) Bradykinin

(C) Captopril

(D) Histamine

(E) Sacubitril

Histamine and bradykinin both cause a marked increase in capillary permeability that is often associated with edema, but histamine is not a peptide. The answer is B.

In a laboratory study of several peptides, one is found that decreases peripheral resistance but constricts veins. Which of the following causes arteriolar vasodilation and venoconstriction?

(A) Atrial natriuretic peptide (ANP)

(B) Bradykinin

(C) Endothelin-1

(D) Substance P

(E) Vasoactive intestinal peptide

Substance P is a potent arterial vasodilator and venoconstrictor. The answer is D

Which of the following endogenous molecules is elevated in heart failure and when given as a drug is a vasodilator with significant renal toxicity?

(A) Angiotensin I

(B) Angiotensin II

(C) BNP (nesiritide)

(D) Histamine

(E) Vasoactive intestinal peptide

BNP is an atrial and brain peptide found in increased amounts in patients with heart failure. The commercial formulation (nesiritide) is approved for use in severe acute heart failure but has significant renal toxicity. The answer is C.

A 50-year-old factory worker presents with cardio-respiratory symptoms and careful workup reveals idiopathic pulmonary hypertension. Which of the following binds endothelin receptors and is approved for use in pulmonary hypertension?

(A) Aliskiren

(B) Capsaicin

(C) Conivaptan

(D) Macitentan

(E) Sacubitril

Aliskiren, a renin inhibitor, is used in primary hypertension. Capsaicin, the “hot” constituent of hot peppers, is the molecule responsible for release of substance P. Conivaptan, an AVP antagonist, is used in hyponatremia. Sacubitril, a neprilysin antagonist, is used in heart failure. Macitentan, an endothelin antagonist, is used in pulmonary hypertension. The answer is D.

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