• Biophysical and molecular mechanism for different cardiac arrhythmias like Brugada, Short QT, Long QT and Sudden Infant Death Syndromes.
• Developmental and gender differences in cardiac electrophysiology and pharmacology.
• Confocal microscopy and Expression analysis by Real Time PCR

My work is focused on studies of ion channels responsible for the movement of ions like sodium, potassium and calcium across the membrane of cardiac cells. Abnormal function of these ion channels secondary to genetic mutations are responsible for the development of abnormal heart rhythms, known as cardiac arrhythmias.

I am also interested in how the function of ion channels changes with development. These studies examine differences the number and function of ion channels in neonate vs. adult hearts as well as differences between the sexes. These studies are critically important in advancing our understanding of cardiac arrhythmias believed to contribute to sudden infant death syndrome (SIDS) and abnormal heart rhythms that place infants and children at risk.

Interaction of antiarrhythmic drugs with mutated ion channels is another interest of mine. I am using patch clamp techniques to assess the interaction of the antiarrhythmic drug lidocaine with a mutated sodium channel responsible for the Brugada syndrome. While Class IB antiarrhythmic drugs like lidocaine usually do not unmask or aggravate the Brugada syndrome, we have uncovered a mutation that sensitizes the heart to lidocaine, permitting the drug to induce electrocardiographic changes that unmask the Brugada syndrome.

In another study, we have recently shown that compound mutations in SCN5A, the gene that encodes the a subunit of the sodium channel, leads to a more severe dysfunction of the sodium channel. Consistent with our biophysical results, members of the family who inherited the double mutation displayed a more severe clinical phenotype of the Brugada syndrome than the individuals inheriting only a single mutation.

Developmental differences in delayed rectifying outward current in feline ventricular myocytes.  
Barajas-Martinez H, Elizalde A and Sánchez-Chapula JA. (2000)
Am J Physiol Heart Circ Physiol; 278(2):H484-92.
PubMed ID:10666079

Frequency-Dependent Effects of 4-Aminopyridine and Almokalant on Action-Potential Duration of Adult and Neonatal Rabbit Ventricular Muscle.
Elizalde A, Barajas-Martinez H, Ricardo Navarro-Polanco N and Sánchez-Chapula JA.
Journal of Cardiovascular Pharmacology; 33(3):352-9.
PubMed ID: 10069668

Differences in outward currents between neonatal and adult rabbit ventricular cells.  
Sanchez-Chapula JA, Elizalde A, Navarro-Polanco N and Barajas-Martinez H
Am J Physiol Heart Circ Physiol; 266(3 Pt 2):H1184-94.
PubMed ID:8160822

Compound heterozygous mutations P336I and I1660L in the human cardiac sodium channel determine the severity of Brugada syndrome.  
Cordeiro JM, Barajas-Martinez H, Hong K, Burashnikov E, Oliva A, Pfeiffer R, Orsino AM, Wu YS, Dan H, Brugada J, Antzelevitch C, Dumaine R, Brugada R.
Circulation; 114(19):2026-33.
PubMed ID:17075016

Identification of two domains involved in the assembly of TRPC channels.  
Pascale K. Lepage, Marc P. Lussier, Hector Barajas-Martinez, Simon M. Bousquet, Alexandre P. Blanchard, Nancy Francoeur, Robert Dumaine and Guylain Boulay.
J Biol Chem; 281(41):30356-64.
PubMed ID:16916799

A novel mutation in the SCN5A gene associated with arrhythmic storm developing Post-MI.  
Hu D, Viskin S, Oliva A, Cordeiro JM, Brugada R, Hong K, Sicouri S, Barajas-Martinez H, Wu YS, Burashnikov E, Antzelevitch C
Hearth Rhythm; 4(8):1072-80.
PubMed ID:17675083

Lidocaine-induced Brugada Syndrome Phenotype Linked to a Novel Mutation and Polymorphism in the Cardiac Sodium Channel.  
Barajas-Martinez H, Hu D, Cordeiro JM, Wu Y, Kovacs R, Henry Meltser, Hong K, Burashnikov E, Brugada R, Antzelevitch C, Dumaine R.
Circulation Research; Submitted, 2007

Larger dispersion of sodium current in female dog ventricle as a potential mechanism for gender-specific incidence of cardiac arrhythmias.  
Barajas-Martinez H, Haufe V, Chamberland C, Blais-Roy MJ, Fecteau MH, Cordeiro JM, Dumaine R.
Am J Physiol Heart Circ Physiol; In revision, 2007.