Ph.D. University of Washington, 1972
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.
Li WY, Strang SE, Brown DR, Smith R'G, Silcox DL, Li S-G, BaldridgeBR, Nesselroade, KP, Jr and Randall, DC. Atomoxetine Changes Rat's HR Response to Stress from Tachycardia to Bradycardia via Alterations in Autonomic Function, Autonomic Neuroscience: Basic and Clinical 154: 48-53, 2010; doi 10.1016/j.autneu.2009.11.003.
Sithisarn T, Bada HS, Dai H, Randall DC, Legan SJ. Effects of perinatal cocaine exposure on open field behavior and the response to Corticotropin Releasing Hormone (CRH) in rat offspring. Brain Res, 1370: 136-144, 2010. PMID 21075083.
Anigbogu CN, Williams DT, Brown DR, Silcox DL, Speakman RO, Brown LV, Karounos DG and Randall DC. Circadian variations in blood pressure, heart rate and HR-BP cross correlation coefficient during progression of diabetes mellitus in rat. Int J Hypertension, Article ID 738689, 2011. doi:10.4061/2011/738689 PMID 21629872.
Randall DC, Speakman RO, Silcox DL, Brown LC, Brown DR, Gong MC, Patwardhan A, Reynolds LR, Karounos DG, Burgess DE and Anigbogu CN. Longitudinal analysis of arterial blood pressure and heart rate response to acute behavioral stress in rats with type 1 diabetes mellitus and in age-matched controls. Front. Physiol. 2:53, 2011. doi 10.3389/fphys.2011.00053 PMID 21904530.
Wang S, Randall DC, Knapp CF, Patwardhan AR, Nelson KR, Karounos DG and Evans JM. Blood pressure regulation in diabetics with and without peripheral neuropathy. Am. J. Physiol. Regul. Integr. Comp. Physiol., 302: R541-R550, 2012. PMID:22049233.
Anigbogu CN, Speakman RO, Silcox DL, Brown LV, Brown DR, Gong MC, Patwardhan AR, Reynolds LR, Karounos DG, Burgess DE, Baldridge BR and Randall DC. Extended Longitudinal Analysis of Arterial Pressure and Heart Rate Control in Unanesthetized Rats with Type 1 Diabetes. Autonomic Neurosci: Basic Clin., 170: 20-29, 2012. doi:10.1016/j.autneu.2012.06.006.
Hoyt RE, Speakman RO, Brown DR, Cassis LA, Silcox DL, Anigbogu CN, Randall DC. Chronic angiotensin-II infusion potentiates heart rate slowing in Sprague-Dawley rats during acute behavioral stress. Autonomic Neurosci: Basic and Clinical. 174: 42-46, 2013. DOI: 10.1016/j.autneu.2012.12.004
Sithisarn T, Bada HS, Charnigo RJ, Legan SJ, Randall DC. Effects of perinatal oxycodone exposure on the cardiovascular response to acute stress in male rats at weaning and in young adulthood. Front Physiol, 4: 85, 2013. doi: 10.3389/fphys.2013.00085.
Sithisarn T, Bada HS, Charnigo RJ, Legan SJ, Randall DC. Effects of perinatal oxycodone exposure on the cardiovascular response to acute stress in male rats at weaning and in young adulthood. Front Physiol, 4: 85, 2013. doi: 10.3389/fphys.2013.00085. PMID: 23630500
Cheng R, Shang Y, Wang S, Evans JM, Rayapati A, Randall DC, Yu G. Near-infrared diffuse optical monitoring of cerebral blood flow and oxygenation for the prediction of vasovagal syncope. J Biomed Optics, 19: 2014. Doi: 10.1117/JBO.19.1.017001. PMID: 24402372