Atrial myocytes

F21. Fukuda, Y., Hirata, Y., Yoshimi, H., Kojima, T., Kobayashi, Y Yanagisawa, M and Masaki, T., Endothelin is a potent secretagogue for atrial natriuretic peptide in cultured rat atrial myocytes. Biochem. Biophys. Res. Commun. 155,167-172 (1988). 

In Phase I clinical trials with stable renal transplant patients, FTY720 led to a transient reduction in the number of circulating lymphocytes whilst being well-tolerated. Treatment was associated with a mild reduction in heart rate that was maximal 6 h after the first dose and returned to baseline with continuous treatment [52,53]. The mild effect on heart rate is believed to arise from SlPj and/or SlP3-mediated activation of G-protein-gated inwardly rectifying potassium (GIRK) channels in atrial myocytes [54-56]. 

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. 

Biinemann, M., Brandts, B., and Pott, L. (1996). Downregulation of muscarinic M2 receptors linked to K+ current in cultured guinea-pig atrial myocytes. J. Physiol. 494, 351-362. 

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. 

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). 

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. 

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. 

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... 

ANP is a 28-amino-acid peptide first discovered by de Bold et al. (2). It is released from heart atrial myocytes in response to a local arterial wall stretch. ANP acts on outer adrenal cells to decrease aldosterone production and blood pressure, increase salt and water excretion, and transudate plasma water to the interstitium (3). 

M.Y. Heinke, M. Yao, D. Chang, R. Einstein and dos Remedios, Apoptosis of ventricular and atrial myocytes from pacing-induced canine heart failure, Cardiovasc. Res. 49, 127-134 (2001). 

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... 

Sun, Z.-Q., Ojamaa, K., Nakamura, T.Y., Artman, M., Klein, I. and Coetzee, W. (2001) A thyroid hormone increases pacemaker activity in rat neonatal atrial myocytes. Journal of Molecular and Cellular Cardiology, 33, 811-824. 

Shroff, S. G., Saner, D. R., and Lai, R. 1995. Dynamic micromechanical properties of cultured rat atrial myocytes measured by atomic force microscopy. Am J Physiol 269, C286-292. 

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. 

Scherer RW, Lo CF, Breitweiser GE. Leukotriene C4 modulation of muscarinic current activation in bullfrog atrial myocytes. J Gen Physiol 1993 102 125-141. 

Pike, G.K., Bretag, A.H., and Roberts, M.L., Modification of the transient outward current of rat atrial myocytes by metabolic inhibition and oxidant stress, J. Physiol (Land.), 470, 365,1993. 

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