March 22, 2002
Volume XXXV, No. 12


Of Note

Who's New


Heart, brain signals under study in four laboratories

Signals, signals, signals. When you get right down to it, the human body is the world's most complex communications network.

Four outstanding scientists in the department of physiology at the Health Science Center are among the many who utilize National Institutes of Health and American Heart Association (AHA) funding to study the amazing wiring of the body. They are contributing highly technical "building blocks" of understanding that, one day, could improve treatments for high blood pressure (hypertension), congestive heart failure, arrhythmias, congenital heart defects and epilepsy.


Dr. Glenn M. Toney, assistant professor, has identified a novel mechanism by which elevated dietary salt can increase sympathetic nerve activity. Activity among the sympathetic nerves, which supply the heart and blood vessels, is a major controller of cardiovascular function. "There is considerable evidence that sympathetic nerve activity becomes dramatically elevated in salt-sensitive cardiovascular diseases such as hypertension and congestive heart failure," he said. "We will further explore the pathway we have identified, which involves release in the brain of a peptide neurotransmitter called angiotensin II." An AHA Established Investigator Grant funds the research, along with a grant from the National Heart, Lung and Blood Institute (NHLBI).


Dr. James D. Stockand, assistant professor, studies cellular regulation of blood pressure. He particularly is interested in how a hormone, aldosterone, controls salt handling by the kidney. "Most hypertension likely involves multiple gene defects and environmental factors," Dr. Stockand said. "Recently, we and others in the field have made many important discoveries in this area. Several of the key cellular mediators of aldosterone have been identified and their mechanisms of action for controlling salt handling by the kidney have become clearer. It is likely that defects in these cellular mediators or improper regulation of their activity play some role in hypertension." Grants from the AHA and the National Institute of Diabetes and Digestive and Kidney Diseases support his research.


Dr. Anthony B. Firulli, assistant professor, examines the process by which cells make "fate decisions" and become programmed to a particular tissue lineage. His studies focus on transcription factors called dHAND and eHAND, which are important for normal heart development. "Transcription factors are genes that control the expression of other genes, functioning like a complex 'on/off switch' determining the genes to be expressed in any particular cell," Dr. Firulli said. "The hope is that gaining understanding of how HAND genes function in the developing heart will add insight into the understanding of the molecular programs that control taking an immature cell to a functional heart cell." The NHLBI supports his studies.


Dr. Mark S. Shapiro, assistant professor, studies two important electrical currents carried by potassium ions critical to the function of the nervous and cardiovascular systems. He focuses on signaling pathways that act on these currents. One pathway acts on the "M current," which regulates the release of neurotransmitters and the excitability of nerve cells. Another acts on the "IKS current," which helps to maintain normal rhythm in the heart. "The human genes responsible for these two ionic currents were identified from genetic analysis of inherited forms of epilepsy in the brain and arrhythmias in the heart," Dr. Shapiro said. "The relevance of our project to medicine is very high, as these types of signaling pathways underlie the regulation of many tissues and organs of the body." The AHA Texas Affiliate and the National Institute of Neurological Disorders and Stroke support his research.

Signals, signals, signals. Each of these researchers is concerned with the communication that regulates our health every second of our lives.