scholarly journals Direct and Indirect Effects of Pseudoephedrine on the Intrinsic Conduction System of the Embryonic Chicken Heart

2015 ◽  
Vol 12 (3) ◽  
Author(s):  
Samely Gonzalez ◽  
Fatima Afzal ◽  
Jacqueline McLaughlin
Keyword(s):  
Heart Rate ◽  
Indirect Effects ◽  
Heart Development ◽  
Adrenergic Receptors ◽  
Nasal Congestion ◽  
Conduction System ◽  
Direct And Indirect Effects ◽  
Over The Counter ◽  
Chicken Heart ◽  
Intrinsic Conduction

Pseudoephedrine (PSE) is an over the counter (OTC) medication used to temporarily relieve nasal congestion, hay fever or other upper respiratory allergies by shrinking blood vessels in the nasal passages. Aside from its vasoconstriction properties it is also known to elevate heart rate, and blood pressure, thus being a sympathomimetic drug. There are two hypotheses on how this drug increases heart rate (HR): (1) a direct mechanism wherein PSE works by binding to adrenergic receptors in the heart’s intrinsic conduction system; and, (2) an indirect mechanism wherein PSE causes the release of norepinephrine from sympathetic nerves to activate adrenergic receptors. This research utilized the chick embryonic heart as a model system to examine the chronotropic effects and mechanisms of PSE on the developing vertebrate heart. Research suggests that this drug has both direct and indirect effects, and induces dangerous heart arrhythmias such as atrial flutter, in high doses. KEYWORDS: Pseudophedrine, Sympathomimetic Drugs, Pseudophedrine and Pregnancy, Pseudophedrine and Norepinephrine, Pseudophedrine Related Arrhythmias, Over–the-counter Drugs; Chick Heart Development

scholarly journals Nkx2.5 is essential to establish normal heart rate variability in the zebrafish embryo

2017 ◽  
Vol 313 (3) ◽  
pp. R265-R271 ◽  
Author(s):  
Jamie K. Harrington ◽  
Robert Sorabella ◽  
Abigail Tercek ◽  
Joseph R. Isler ◽  
Kimara L. Targoff
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Heart Development ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Loss Of Function ◽  
Normal Heart ◽  
Wild Type ◽  
Cardiac Health ◽  
Normal Heart Rate

Heart rate variability (HRV) has become an important clinical marker of cardiovascular health and a research measure for the study of the cardiac conduction system and its autonomic controls. While the zebrafish ( Danio rerio) is an ideal vertebrate model for understanding heart development, HRV has only recently been investigated in this system. We have previously demonstrated that nkx2.5 and nkx2.7, two homologues of Nkx2–5 expressed in zebrafish cardiomyocytes, play vital roles in maintaining cardiac chamber-specific characteristics. Given observed defects in ventricular and atrial chamber identities in nkx2.5−/− embryos coupled with conduction system abnormalities in murine models of Nkx2.5 insufficiency, we postulated that reduced HRV would serve as a marker of poor cardiac health in nkx2.5 mutants and in other zebrafish models of human congenital heart disease. Using live video image acquisition, we derived beat-to-beat intervals to compare HRV in wild-type and nkx2.5−/− embryos. Our data illustrate that the nkx2.5 loss-of-function model exhibits increased heart rate and decreased HRV when compared with wild type during embryogenesis. These findings validate HRV analysis as a useful quantitative tool for assessment of cardiac health in zebrafish and underscore the importance of nkx2.5 in maintaining normal heart rate and HRV during early conduction system development.

Direct and indirect effects of dynamic social impact

2005 ◽  
Author(s):  
Dana M. Binder ◽  
Martin J. Bourgeois ◽  
Christine M. Shea Adams
Keyword(s):  
Indirect Effects ◽  
Social Impact ◽  
Direct And Indirect Effects
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