Using a rat model for high blood pressure (hypertension), a common chronic cardiovascular condition, a University of South Florida team found that preexisting hypertension altered normal reflexes in the lungs to affect autonomic regulation of the heart when an irritant mimicking air pollution was inhaled. In particular, hypertension appeared to shift the reflex response from the ‘fight-or-flight’ parasympathetic nervous system to the sympathetic nervous system, which controls involuntary responses like heart rate while the body is at rest.
Source: EurekaAlert, https://www.eurekalert.org