Temperature dependent contribution of Ca2+ transporters to relaxation in cardiac myocytes: important role of sarcolemmal Ca2+ -ATPase

• Autorzy: Mackiewicz U. , Lewartowski B.
• Języki publikacji: EN

Abstrakty

EN

Activities of Ca2+-ATPase of sarcoplasmic reticulum (SERCA) and Na+/Ca2+ exchanger (NCX) involved in cellular Ca2+ turnover greatly change in hypertrophied and failing hearts. Unfortunately, contribution of these proteins as well as of the sarcolemmal Ca2+-ATPase (PMCA) to cellular Ca2+ turnover has been investigated almost exclusively at room temperature. PMCA is of particular interest since it may affect activity of calcineurin and nNOS. Therefore the objective of this study was to reinvestigate contribution of SERCA, NCX and PMCA to cell relaxation and the effect of PMCA on cell contraction at 37°C. Myocytes isolated from the ventricles of guinea pig and rat hearts and incubated with Indo-1 were field stimulated at the rate of 60/min. Contribution of SERCA, NCX and PMCA was calculated from the rate constants of the decaying components of electrically stimulated Ca2+ transients or of the transients initiated by caffeine dissolved in normal Tyrode or in 0Na, 0Ca Tyrode. Increase in temperature from 24 to 37°C increased the relative contribution of NCX from 6.1% to 7.5% in rat and from 21.3 to 51.9 % in guinea pig at the expense of SERCA. The contribution of the PMCA to relaxation in both species increased upon rise in temperature from 24 % to 37°C from negligible values to 3.7 %. In both species amplitude of Ca2+ transients was at 24°C nearly twice as high as at 37°C. It was nearly doubled by carboxyeosine (CE), a PMCA blocker at 37°C but was hardly affected at 24°C. The effects of CE were concentration-dependent and conformed with the degree of inhibition of activity of PMCA. Conclusions: PMCA plays an important role in regulation of myocardial contraction despite its small contribution to relaxation. In guinea pig but not in rat relative contribution of SERCA and NCX to relaxation is highly temperature dependent.

Słowa kluczowe

EN

sarcoplasmic reticulum; cardiac myocyte; temperature; ventricular myocyte; calcium transporter

• Wydawca: -
• Czasopismo: Journal of Physiology and Pharmacology
• Rocznik: 2006
• Tom: 57
• Numer: 1
• Opis fizyczny: p.3-15,fig.,ref.

Twórcy

autor

Mackiewicz U.

• Medical Center of Postgraduate Education, Marymoncka Str.99, 01-813 Warsaw, Poland

autor

Lewartowski B.