Research Highlights from Conference on Autonomic Regulation of Cardiovascular Function in Health and Disease

New research being presented at latest conference sponsored by the American Physiological Society

Newswise — BETHESDA, Md. (June 27, 2012) —The latest conference to be sponsored by the American Physiological Society is “Autonomic Regulation of Cardiovascular Function in Health and Disease,” which will be held July 7-10, 2012 in Omaha. The full program is available online. Highlights of the symposia and poster presentations include:

Why Do Some People Faint When They Stand?Normally, a host of compensatory mechanisms kicks into gear when you go from sitting or lying to standing, increasing blood pressure and blood flow to the head to keep you from fainting. This process, known as orthostasis, is automatic and typically kicks in quickly. Though momentary dizziness is common, a small proportion of people suffer from a condition known as orthostatic intolerance, in which going into a standing position leads to a drastic drop in blood pressure, sometimes leading to feeling faint or a momentary loss of consciousness. Recent research being presented at the meeting suggests that the sympathetic nervous system and dysfunction in a variety of autonomic processes could be to blame for orthostatic intolerance. (Symposium abstract #005 – Monday, July 9)

BMI Could Change Heart Rate VariabilityA body mass index (BMI) that’s either on the high or low side has been linked with a number of health problems. In new research being presented at this meeting, scientists find that a low BMI can affect heart rate variability, a sign of healthy heart function. The researchers examined heart rate variability in 123 female volunteers, most of which had a healthy BMI, and others considered either thin or just short of obese. They recorded speed-ups and slow-downs in heart rate both when these subjects were at rest and when they were stressed. Findings showed that when the thin subjects were stressed, their heart rates were significantly elevated and they had less heart rate variability compared to the normal or pre-obese subjects. The results in this poster presentation suggest that BMI can have a significant effect on heart rate variability. (Poster abstract #074 – Monday, July 9)

Testosterone and Salt-Induced High Blood PressureIn animal models of salt-induced high blood pressure, blood pressure is usually higher in males than in females. Theories have abounded on why this might occur, but little research had examined the role of testosterone directly. Researchers present new findings at this meeting on how testosterone might be involved. In their study, they examined rats that had been castrated, those who had sham operations but weren’t actually castrated, and those who had been castrated but took replacement testosterone. When these animals were fed a high-salt diet, results showed that castration eased high blood pressure, but testosterone replacement obliterated that improvement. Additional findings suggest this effect might be due to testosterone blunting the sensitivity of the baroreflex, a natural feedback loop the body uses to control blood pressure. (Poster abstract #043 – Monday, July 9)

How the Blood-Brain Barrier Might Be Responsible for High Blood PressureDespite decades of study, researchers still aren’t sure what factors are responsible for chronically elevated blood pressure. In new research being presented at the meeting, scientists suggest that the blood-brain barrier in the brainstem—the primitive brain area responsible for many of the body’s basic functions, such as breathing, heart rate, sleeping, and eating—could play a key role salt-induced baroreflexin regulating blood pressure. The researcher will present evidence showing that tiny blood vessels that supply the brainstem become inflamed in animal models with high blood pressure, potentially because sticky molecules trap inflammatory white blood cells. That leads to impaired circulation, and in turn, impaired function of the brainstem, leading high blood pressure to develop. (Symposium abstract #060 – Tuesday, July 10)

Additional PresentationsSessions offered will cover the mechanisms behind hypertension, heart failure, diabetes and panic disorders, among others. Topics will include the role of the autocrine, paracrine and endocrine mediators in reflexes and areas of the central nervous system that are known to regulate sympathetic function. Symposia and poster abstracts will focus on reactive oxidant stress, nitric oxide, angiotensin II, angiotensin (1-7), glutamate, GABA and the transcriptional and translational regulation of the receptors for many of these mediators. The full program is available online. ###

Members of the press are invited to attend the Autonomic Regulation of Cardiovascular Function in Health and Disease conference. For further information contact Donna Krupa at [email protected], 301.634.7209 or @Phyziochick.

Physiology is the study of how molecules, cells, tissues and organs function to create health or disease. The American Physiological Society (APS; www.the-APS.org/press) has been an integral part of the discovery process for 125 years. To keep up with the science, follow @Phyziochick on Twitter.