A team of researchers from the University of Chicago have figured out the link between sleep apnea and hypertension. The findings have led to a potential treatment that’s already been tested in rodent trials. The details are in a paper just published in the journal Science Signaling.
Patients with sleep apnea have trouble breathing while asleep and sometimes stop breathing completely. The disorder, which is especially common among adult men, is also associated with high blood pressure. In serious cases, this can lead to strokes.
Researchers used rats to study the events that are triggered by sleep apnea. They found that the first problem is oxygen deprivation. As patients slow or stop their breathing, blood-oxygen levels drop. A group of cells in the carotid body, located in the neck’s carotid arteries, detect this change. The carotid body cells then send out signals to increase breathing rates to bring oxygen levels back up. The cells produce reactive oxygen species which inactivate an enzyme called heme oxygenase-2. When the enzyme is inactive, hydrogen sulfide builds up and acts as a signal for the body to take in more oxygen. The problem is that this also causes the constriction of blood vessels, increasing blood pressure.
The team used this knowledge to develop a possible treatment. They used a drug called cystathionine-y-lyase inhibitor L-propargylglycine (L-PAG) to inhibit the enzyme responsible for producing hydrogen sulfide. By disrupting the enzyme, the signaling pathway is also interrupted, preventing the increase of blood pressure. The researchers tested the drug on rats and found that it successfully prevented sleep apnea-related hypertension.
Researchers have now discovered the specific pathway that links sleep apnea to high blood pressure. Medications that block this pathway can treat this form of hypertension. The drug L-PAG has already been tested on rats and the authors are hopeful about future human trials.
Guoxiang Yuan et al. H2S production by reactive oxygen species in the carotid body triggers hypertension in a rodent model of sleep apnea. Science Signaling (2016).