[Effect of a new arginine analog on isoproterenal-induced Ca2+ transients in cultured rat cardiac myocytes].
OBJECTIVE
To investigate the effects of a novel tripeptide analog of arginine on isoproterenol (ISO), a beta-adrenergic receptor agonist, induced the change in concentration transient cytosolic free calcium in cultured neonatal rat cardiac myocytes (CMs).


METHODS
The expression of inducible nitric oxide synthase (iNOS) was induced in cultured neonatal rat CMs by stimulation with lipopolysaccharide (LPS) and interleukin-6 (IL-6) for 24 h, and quantitatively measured using Western blotting. The CMs were incubated in the presence of the new arginine analog for 6 h and the changes of fluorescence signal of free calcium in response to isoproterenol (ISO) treatment were measured under laser scanning confocal microscope.


RESULTS
Incubation of the CMs for 24 h in the presence of IL-6 and LPS resulted in significantly increased nitric oxide (NO) production, and also in increased iNOS protein accumulation in the cells. Specific inhibition of iNOS by the new arginine analog substantially inhibited NO production and increased the peak value of ISO-induced Ca2+ transient.


CONCLUSIONS
The new arginine analog strongly inhibits IL-6 and LPS-induced NO production and increases beta-adrenergic responsiveness in cultured neonatal rat CMs.
Sun
Fei
F
Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. sunfei@fimmu.com
Wu
Sai-zhu
SZ
Zhang
Xiao-tian
XT
D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D007545:Isoproterenol / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D009842:Oligopeptides; C521328:arginyl-glutamyl-arginine; D001120:Arginine; D007545:Isoproterenol; D002118:Calcium