Physiology

DAVID C. RANDALL, Ph.D. Professor Ph.D. University of Washington, 1972 Office: MN-526 Medical Center 0298 Tel: (859) 323-6041 Lab: MN-554 Tel: (859) 323-5436 E-mail: randall@uky.edu Curriculum Vita (pdf)

Research in this laboratory focuses on the nervous control of the heart and circulation. Most experiments are conducted in un-anesthetized subjects since anesthetics dramatically alter the way in which the nervous system operates. A typical study uses a carefully defined behavioral test to challenge the nervous system and activate the cardiac sympathetic and parasympathetic nerves. We have shown that surgical removal of certain para-sympathetic nerve cells on the heart eliminates the earliest heart rate increase to a behavioral challenge. We are now determining the precise role of other cardiac ganglia in controlling the HR conditional response.

In a second experiment we are directly recording sympathetic nerve activity (SNA) and arterial blood pressure (BP) in the un-anesthetized rat. The sympathetic nervous system is one of the major controllers of arterial pressure. The goal of these experiments is to study the relationship between SNA and BP as precisely as possible. For example, the rat responds to a conditioning trial by increasing its pressure within about 1 sec. of the onset of the tone; this increase in BP lasts 3-5 sec. We showed that this blood pressure change is preceded by a sudden, short burst of nerve activity. Therefore, the 6 sec. long increase in blood pressure is due to a neural event lasting only about ½ sec.; in a sense, this is like the flight of a baseball following a very brief contact with a bat. We are now using some powerful mathematical techniques to study this phenomenon.

Recent Publications:

El-Wazir YM, Li S-G, Smith RG, Silcox DL, Brown DR, and Randall DC. Parasympathetic Response to Acute Stress is Attenuated in Young Zucker Obese Rats. Autonomic Neuroscience: Basic and Clinical, in press; doi: 10.1016/j.autneu.2008.07.004.

Aslan SC, Randall DC, Donohue KD, Knapp CF, Patwardhan AR, McDowell SM, Taylor RF and Evans, JM. Blood pressure regulation in neurally intact human vs. acutely injured paraplegic and tetraplegic patients during passive tilt. Am. J. Physiol. Regul. Integr. Comp. Physiol., 292: R1146 - R1157, 2007.

Brown DR, Cassis LA, Silcox DL, Brown LV and Randall DC. Empirical and theoretical analysis of the extremely low frequency arterial blood pressure power spectrum in unanesthetized rat. Am. J. Physiol. Heart Circ. Physiol., 291: H2816 - H2824, 2006.

El-Wazir YM, Li SG, Williams DT, Sprinkle AG, Brown DR and Randall DC. Differential Acquisition of Specific Components of a Classically Conditioned Arterial Blood Pressure Response in Rat. Am. J. Physiol. Regul. Integr. Comp. Physiol. 289: R784 - R788, 2005.

Randall, DC, Baldridge BR, Zimmerman EE, Carroll JJ, Speakman RO, Brown DR, Taylor RF, Patwardhan A and Burgess DE. Blood pressure power within frequency range around 0.4 Hz in rat conforms to self-similar scaling following spinal cord transection. Am. J. Physiol. Regul. Integr Comp. Physiol. 288: R737 - R741, 2005.

Other Publications