Professor of Physiology
Smooth Muscle Research Centre
Dundalk Institute of Technology
0429 370 564
0429 370 509Research Interests My research career began in 1997 when I undertook a project as part of my B.Sc thesis into the responsiveness of lymphatic vessels to 5-HT. Later that year I started a Ph.D with Dr Keith Thornbury into the electrical basis of tone in the urethra. During my Ph.D we discovered a population of specialised pacemaker cells located in the smooth muscle wall of the urethra which we termed 'interstitial cells'. Research into the function of these cells forms much of the basis for current studies in our laboratory. Upon completion of my Ph.D in 2000 I moved to the United States to work with the late Professor Burton Horowitz in the department of Physiology and Cell Biology in the University of Nevada Medical School. Under his mentorship I learned new molecular biology techniques including use of gene arrays, which I used to investigate the role of interstitial cells of cajal in the gastric fundus as well, as the role of novel potassium channels in a range of smooth muscle preparations.
Upon returning to the Smooth Muscle Group in Queens Belfast in 2003 I have attempted to introduce a molecular approach to help unravel the role of interstitial cells in the rabbit urethra. I have also turned my attention to investigate the calcium signals which underlie pacemaker currents in these cells.
In 2005 I, along with Mark Hollywood, Keith Thornbury and Noel McHale have been appointed to the Dundalk Institute of Technology where we have developed a new Smooth Muscle Research Centre where we are continuing investigations into urethral smooth muscle as well as corpus cavernosum and lymphatic vessels. Publications 2005 L.M. Johnston, Gerard P. Sergeant, M.A. Hollywood, K.D. Thornbury and N.G. McHale. Calcium oscillations in interstitial cells of the rabbit urethra (Journal of Physiology in press).2005 Gerard P Sergeant, Gregory C. Amberg, Susumu Ohya, James A. Reihill, Brian A. Perrino, Yuji Imaizumi, Burton Horowitz, Kenton M. Sanders and Sang Don Koh. Regulation of Kv4.3 current by Ca2+-calmodulin-dependent protein kinase II. Am J Physiol (Cell Physiology) 2005 Feb;288(2):C304-13.2004 Michael Craven, Gerard P Sergeant, Mark A Hollywood, Noel G McHale, and Keith D Thornbury. Modulation of spontaneous Ca2+-activated Cl- currents in the rabbit corpus cavernosum by the NO/cGMP pathway. J Physiol published February 6, 2004, 10.1113.2003 Ohya S, Sergeant GP, Greenwood IA, Horowitz B. Molecular variants of KCNQ channels are expressed in murine portal vein myocytes: A role in delayed rectifier current. Circ Res. 2003 May 16;92(9):1016-23. 2003 Hollywood MA, Sergeant GP, McHale NG, Thornbury KD. Activation of Ca2+-activated Cl- current by depolarizing steps in rabbit urethral interstitial cells. Am J Physiol Cell Physiol. 2003 Aug;285(2):C327-332002. 2002 Walker RL, Koh SD, Sergeant GP, Sanders KM, Horowitz B. TRPC4 currents have properties similar to the pacemaker current in interstitial cells of Cajal. American Journal of Physiology (Cell Physiology). Dec; 283(6):C1637-C1645.2002 Sergeant GP, Large RJ, Beckett EA, McGeough CM, Ward SM, Horowitz B. Microarray comparison of normal and W/Wv mice in the gastric fundus indicates a supersensitive phenotype. Physiological Genomics. Oct 2; 11(1):1-9.2002 Sergeant GP, Thornbury KD, McHale NG, Hollywood MA. Characterization of norepinephrine-evoked inward currents in interstitial cells isolated from the rabbit urethra. American Journal of Physiology (Cell Physiology). Sep; 283(3):C885-94.2001 Koh SD, Monaghan K, Sergeant GP, Ro S, Walker RL, Sanders KM, Horowitz B. TREK-1 regulation by nitric oxide and cGMP-dependent protein kinase. An essential role in smooth muscle inhibitory neurotransmission. Journal of Biological Chemistry. Nov 23; 276(47):44338-46.2001 Sergeant GP, Hollywood MA, McHale NG, Thornbury KD. Spontaneous Ca2+ activated Cl- currents in isolated urethral smooth muscle cells. Journal of Urology. Sep; 166(3):1161-6.2001 Sergeant GP, Hollywood MA, McCloskey KD, McHale NG, Thornbury KD. Role of IP(3) in modulation of spontaneous activity in pacemaker cells of rabbit urethra. American Journal of Physiology (Cell Physiology). May; 280(5):C1349-56.2000 Sergeant GP, Hollywood MA, McCloskey KD, Thornbury KD, McHale NG. Specialised pacemaking cells in the rabbit urethra. Journal of Physiology. Jul 15; 526 Pt 2:359-66. Grant Income 2005 Health Research Board: Research Fellowship.2005 National Institutes of Health: Public Announcement Award titled ‘Cellular Mechanisms underlying myogenic tone in the urethra and its modulation by neurotransmitters’ (C0-PI).