Habo J. Jongsma

Learn More
Intercellular communication between cells of the vessel wall is established by a combination of diffusion and convection of humoral and endothelial factors in the extracellular fluid or by direct intercellular contacts present in the form of gap junctions composed of proteins called connexins. At least connexin (Cx)37, Cx40 and Cx43 are expressed in the(More)
Atrial standstill (AS) is a rare arrhythmia that occasionally appears to be genetically determined. This study investigates the genetic background of this arrhythmogenic disorder in a large family. Forty-four family members were clinically evaluated. One deceased and three living relatives were unambiguously affected by AS. All other relatives appeared(More)
Short term (15 min) effects of activators of protein kinase A (PKA), PKC and PKG on cardiac macroscopic (gj) and single channel (γj) gap junctional conductances were studied in pairs of neonatal rat cardiomyocytes. Under dual whole-cell voltage-clamp, PKC activation by 100 nM TPA increased gj by 16 ± 2% (mean ± S.E.M, n=9), 1.5 mM of the PKG activator(More)
BACKGROUND Prolonged atrial fibrillation (AF) results in electrical, structural, and gap-junctional remodeling. We examined the reversibility of the changes in (ultra)structure and gap junctions. METHODS AND RESULTS Four groups of goats were used: (1) sinus rhythm (SR), (2) 4 months' AF (4 mo AF), (3) 2 months' SR after 4 mo AF (2 mo post-AF), and (4) 4(More)
OBJECTIVE The aim of this work was to target a vital reporter gene in the mouse cardiac conduction system (CS) to distinguish this tissue from the surrounding myocardium in the adult heart. METHODS A transgenic mouse line has been created in which EGFP is expressed under the control of the Cx40 gene. Correlative investigations associating EGFP imaging and(More)
BACKGROUND Connexin 43 (Cx43) is a major determinant of conduction in the ventricular working myocardium of mammals. We investigated the effect of decreased Cx43 expression on conduction velocity and arrhythmogenesis using adult mice with inducible deletion of Cx43. METHODS AND RESULTS Cx43Cre-ER(T)/+ mice, in which 1 coding region of the Cx43 gene was(More)
To assess whether alterations in membrane fluidity of neonatal rat heart cells modulate gap junctional conductance (g j ), we compared the effects of 2mm 1-heptanol and 20 μm 2-(methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)-octanoate (A2C) in a combined fluorescence anisotropy and electrophysiological study. Both substances decreased fluorescence(More)
Alterations in distribution, density, and properties of cardiac gap junctions, which mediate electrical coupling of cardiomyocytes, are considered potentially arrhythmogenic. We recently reported 2 linked polymorphisms within regulatory regions of the gene for the atrial gap junction protein connexin40 (Cx40) at nucleotides -44 (G-->A) and +71 (A-->G),(More)
OBJECTIVE Murine P19 embryonal carcinoma (EC) cells can differentiate into spontaneously beating cardiomyocytes in vitro and have revealed important insight into the early molecular processes of cardiomyocyte differentiation. We assessed the suitability of the P19 cell model for studying cardiac ion channel regulation at the molecular and functional level.(More)
The effects of 8-bromoguanosine 3′:5′-cyclic monophosphate (8Br-cGMP), a membrane-permeant activator of protein kinase G (PKG), were studied on rat and human connexin43 (Cx43), the most abundant gap junction protein in mammalian heart, which were exogenously expressed in SKHep1 cells. Under dual whole-cell voltage-clamp conditions, 8Br-cGMP decreased gap(More)