Human atrial myocytes

Hove-Madsen, L., Llach, A., Bayes-Genis, A., Roura, S., Rodriguez Font, E., Aris, A., and Cinca, J. (2004). Atrial Fibrillation is Associated with Increased Spontaneous Calcium Release from the Sarcoplasmic Reticulum in Human Atrial Myocytes. Circulation 110(11) 1358-63. 

Ouadid H, Seguin J, Dumuis A, Bockaert J, Nargeot J. Serotonin increases calcium current in human atrial myocytes via the newly described 5-hydroxy-tryptamine4 receptors. Mol Pharmacol 1992 41 346-351. 

Sartiani L, De Paoli P, Lonardo G, et al. Does recombinant human interleukin-11 exert direct electrophysiologic effects on. single human atrial myocytes J Cardiovasc Pharmacol 2002 39(3) 425-34. 

Wang Z, Fermini B, Nattel S (1994) Rapid and slow components of delayed rectifier current in human atrial myocytes. Cardiovasc Res 28 1540-1546... 

In contrast to the growing knowledge on the vascular effects of cannabinoids, little is known about cannabinoid-induced direct cardiac effects. The endocannabinoid anandamide (Felder et al. 1996), anandamide amidohydrolase (Bilfinger et al. 1998), and traces of the message for the CBi receptor (Galiegue et al. 1995) have all been detected in the human heart. In a more recent study, the existence of CBi receptors was confirmed in human atrial myocytes by immunoblotting and immunohistochemistry (Bonz et al. 2003). In the same study, it was demonstrated... 

Wang, Z., Feng, J., Shi, H., Pond, A., Nerbonne, J.M., and Nattel, S. (1999) Potential molecular basis of different physiological properties of the transient outward K+ current in rabbit and human atrial myocytes. Circ. Res. 84, 551-561. 

Whereas several peptides besides AVP are known to act synergistically with CRH, the only peptide candidate in humans that inhibits the HPA system at all regulatory levels of the system seems to be atrial natriuretic peptide (ANP). ANP has been shown to inhibit the stimulated release of CRH and ACTH in vitro and in vivo. This could be observed in humans as well, where ANP inhibits the CRH-induced ACTH (Keller et al. 1992), prolactin (Wiedemann et al. 1995), and cortisol secretion (StrOhle et al. 1998). ANP is not only synthesized by atrial myocytes (deBold et al. 1985) and released into the circulation, but is also found in neurons of different brain regions (Tanala et al. 1984) where specific receptors have been found. ANP receptors and immunoreactivity have been found in periventricular and paraventricular hypothalamic nuclei, the LC, and the central nucleus of the amygdala. 

The 5-HT4 receptors modulate the activities of channels and transporters by increasing cAMP levels. These include activation of L-type Ca2+ channels (326), chloride currents in human jejunal mucosa and rat distal colon (330,331), and the If pacemaker current in atrial myocytes (332) and stimulation of aldosterone release from the adrenal glands (333,334), striatal dopamine release (324), hippocampal and frontal cortex acetylcholine release (335,336), and hippocampal 5-HT release (337). 5-HT4 receptors also inhibit various channels, including a KV3.2-like delayed rectifier K+ channel (303), a voltage-activated K+ channel in colliculi neurons (320,338), a Ca2+-activated, afterhyperpolariz-ing, and K+ current in hippocampus (325). 

Pino R, Cerbai E, Calamai G, et al. Effect of 5-HT4 receptor stimulation on the pacemaker current 1(f) in human isolated atrial myocytes. Cardiovasc Res 1998 40 516-522. 

Kvl.5 In human atria, the Kvl.5 presents the ultrarapid delayed rectifier that contributes to the repolarization in the early phase of cardiac action potential. Selective blockers of Kvl.5 channels could be potentially beneficial in the treatment of atrial fibrillation because blocking Kvl. 5 could delay repolarization and prolong refractoriness selectively in cardiac myocytes. Examples for Kvl.5 blockers include AVE0118, S9947, and analogs of diphenyl phosphine oxide (DPO). 

Leptin has been shown to increase hyperplasia of the murine atrial HL-1 cell line as well as pediatric cardiomyocytes (Tajmir et al. 2004). Activation of ERK and phosphatidylinositol 3-kinase was demonstrated and implicated in the increase in cell number. It should be noted that leptin-induced hypertrophy has also been shown in human pediatric ventricular myocytes which was associated with increased ERK, p38, and JAK phosphorylation (Madani et al. 2006). 

Bistola V, Nikolopoulou M, Derventzi A, Kataki A, Sfyras N, Nikou N, Toutouza M, Toutouzas P, Stefanadis C, Konstadoulakis MM (2008) Long-term primary cultures of human adult atrial cardiac myocytes cell viability, structural properties and BNP secretion in vitro. Int J Cardiol 131(1) 113—122. doi 10.1016/j.ijcard.2007.10.058... 

NESIRITIDE Nesiritide (natrecor), a recombinant form of human brain natriuretic peptide (BNP), is FDA-approved for treatment of dyspnea due to congestive heart failure. The natriuretic peptides—atrial natriuretic peptide (ANP), BNP, and C-type natriuretic peptide—are a family of endogenous hormones that possess potent natriuretic, diuretic, and vasodilator properties. BNP is secreted by ventricular cardiac myocytes in response to stretch circulating levels of BNP correlate with the severity of heart failure. In the setting of heart failure, the effects of BNP counteract the effects of Angll and NE by producing vasodilation, natriuresis, and diuresis. 

Another potential cellular mechanism by which a low thyroid function may favor the progression of HF is the alteration of the cardiomyocyte cytoskeleton. Alteration in the myocyte cytoskeleton has also been documented in a human model of prolonged (10 days) T3-deprived atrial myocardial cultured tissue (Forini et al., 2001). Aside from the use of human cardiac tissue, the unique feature of the cited study was the culture technique, which allowed preservation of the three-dimensional architecture of the tissue. In this study. 

Q. Zhang, J. Jiang, P. Han, Q. Yuan, J. Zhang, X. Zhang, Y. Xu, H. Cao, Q. Meng, L. Chen, Direct differentiation of atrial and ventricular myocytes from human embryonic stem cells by alternating retinoid signals. Cell Res 21, 579-587 (2011). 

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