Ronald E. McNair Program


Antoinette Dawson
 Name: Antoinette Dawson
School: Tougaloo College
Major: Biology
Mentor: Dr. Sean Wilson and Dr. Ziaeddin Shariat-Madar
Expected Graduation Date: May 2010 
Organizations & Honors: 
  • Gates Millennium Scholar 
  • Jackson Heart Study Scholar 
  • Minority Association of Premedical Students 
  • Tougaloo Ambassador of Meritorious Scholars 
  • Alpha Lambda Delta Honor Society 
  • Pre-Health Club Society 
  • Delta Sigma Theta Sorority, Incorporated 
  • Early Identification Candidate for Brown Medical School 
  • 2008 Summer Multidisciplinary International Research Training Program (MIRT) Participant 
  • Ronald E. McNair Scholar 
E-MAIL: antdawson88@yahoo.com 

ABSTRACT

Serotonin Mediated Ca2+Signaling Dynamics in Pulmonary Arterial Myocytes and the Combined Influence of Maturation and High-Altitude Exposure

The pulmonary vasculature regulates the flow of blood through the lung in response to blood oxygenation. Under normal oxygenated conditions, a dynamic equilibrium is established between the pulmonary vasculature and the lungs, which maintains the ratio of ventilation to perfusion. However, long-term exposure to chronic hypoxia leads to changes in the pulmonary vasculature, which aids in the development of pulmonary hypertension. Studies also show that long-term maternal hypoxia compromises lung development in the fetus and may be a risk factor for the development of Persistent Pulmonary Hypertension in Newborns (PPHN). Unlike systemic hypertension, pulmonary hypertension is difficult to treat and the prognosis is poor. Pulmonary arterial smooth muscle cells (PASMCs) contract in response to the release of serotonin, which triggers the release of calcium. The effect of serotonin in the development of PPHN and pulmonary hypertension was determined.  

 
This study tested the hypothesis that hypoxia leads to alterations in the calcium signaling dynamics in the sheep PASMCs in response to serotonin exposure. This was examined by using confocal fluorescence microscopy of PASMCs in-situ from fetal and adult sheep that were loaded with the calcium indicator Fluro-4. The results show that serotonin increases calcium signaling responses in both normoxic and hypoxic fetal and adult sheep PASMCs. Further, the basal activity is greater in PASMCs from adult hypoxic animals as compared to normoxic animals. Maturation leads to an increase in cell firing rate and the number of responsive cells. These findings provide the first evidence that maturation and long term hypoxia alter calcium signaling. This may be important to the development of therapeutics for the treatment of pulmonary hypertension.