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Pulmonary hypertension is a form of high blood pressure that affects the blood vessels in the lungs. In the womb, the blood pressure in the fetus’ lungs is normally high. Once a baby is born, there is a switch from a high to low blood pressure. When this fails to happen, the baby develops pulmonary hypertension.

Pulmonary hypertension occurs in about six in 1,000 newborn babies each year and may occur more frequently at high altitudes. Despite all of our recent advances, many infants do not respond to treatment and as many as 33 percent of these babies die. Because current treatments are not entirely effective, many groups of researchers are working to find new treatments.

In a recent article, Chilean researchers observed 10 lambs that were conceived and born at high altitude, which causes pulmonary hypertension, and compared them to lambs born at a low altitude. The goal was to see if giving a drug called fasudil to young lambs would reduce the development of pulmonary hypertension in the high-altitude lambs.

Fasudil targets a molecular pathway known as the RhoA/ROCK pathway, which is thought to play a major role in causing pulmonary hypertension. Previous studies have shown that fasudil lowers lung blood pressure in adults, but it wasn’t known whether the drug would also work in infants. The researchers in this study found that fasudil opened up (dilated) lung blood vessels in the lambs born at high altitude and lowered pulmonary blood pressure. The results show that fasudil and other drugs that intervene on the RhoA/ROCK pathway have the potential to decrease pulmonary hypertension in infants, too. These drugs may be a new tool in a physician’s arsenal, possibly preventing death and other serious complications in babies born with pulmonary hypertension.

Rachel Luehrs is a graduate student in the Bates Laboratory of Pulmonary and Developmental Physiology at the University of Iowa.