Enzymes that make the gas nitric oxide (NO) not only protect the heart from damage due to high blood pressure or a heart attack, but also promote heart failure through overgrowth and enlargement of the muscle tissue, say animal researchers at Johns Hopkins. The Hopkins study, to be published in the May 2 edition of the Journal of Clinical Investigation, is believed to be the first to suggest future therapies for heart failure using chemical cofactors that control the enzymes’ action. Nitric oxide’s extensive portfolio of natural effects includes the ability to expand coronary arteries, which improves blood flow, and to help regulate the strength of the heart’s contraction, notes cardiologist David Kass, M.D., a specialist in enlarged hearts, or hypertrophy, and a professor at The Johns Hopkins University School of Medicine and its Heart Institute.