COMPARISON OF CALCIUM-CURRENT IN ISOLATED ATRIAL MYOCYTES FROM FAILING AND NONFAILING HUMAN HEARTS

Citation
Th. Cheng et al., COMPARISON OF CALCIUM-CURRENT IN ISOLATED ATRIAL MYOCYTES FROM FAILING AND NONFAILING HUMAN HEARTS, Molecular and cellular biochemistry, 157(1-2), 1996, pp. 157-162
Citations number
30
Categorie Soggetti
Biology,"Cell Biology
ISSN journal
03008177
Volume
157
Issue
1-2
Year of publication
1996
Pages
157 - 162
Database
ISI
SICI code
0300-8177(1996)157:1-2<157:COCIIA>2.0.ZU;2-W
Abstract
To identify possible alterations of the L-type calcium currents (I-Ca, I-L) in cardiomyopathy, I-Ca,I-L were recorded in atrial myocytes diss ociated from the nonfailing heart (NF) of patients undergoing correcti ve open-heart surgery and explanted failing heart (FH) of patients wit h dilated cardiomyopathy undergoing heart transplantation. The patch-c lamp technique was applied in the single-electrode whole-cell mode. Th e electrophysiological properties of I-Ca,I-L, including cell capacita nce and current density, were similar in atrial myocytes from both gro ups of patients. Further to identify possible alterations of the myoca rdial beta-adrenergic pathway in cardiomyopathy, we examined the effec ts of isoproterenol, forskolin, 8-Br-cAMP and IBMX on I-Ca,I-L in both groups of atrial myocytes. Perfusion of isoproterenol (1 mu M) signif icantly increased the peak I-Ca,I-L by 51.5+/-44% in 6 atrial myocytes from NF but increased only by 135+/-25% in 27 atrial myocytes from FH . However, forskolin (1 mu M) or 8-Br-cAMP (0.1 mM) increased the peak I-Ca,I-L to a similar extent in atrial myocytes from NF and FH. IBMX (20 mu M) also induced a comparable increase in the peak I-Ca,I-L by 2 13+/-31% (n=5) and 207+/-59% (n=4) in atrial myocytes from NF and FH, respectively. The above findings suggest that in atrial myocytes obtai ned from FH the beta-adrenoceptor numbers might be decreased but no im pairment of the signal transduction cascade occurred beyond the GTP bi nding proteins level.