Simultaneous recording of Indo‐1 flourescence and Na+/Ca2+ exchange current reveals two components of Ca2+‐release from sarcoplasmic reticulum of cardiac atrial myocytes

FEBS Letters

Pott, Lutz¹  Callewaert, Geert²  Lipp, Peter¹  Carmeliet, Edward² 

[1] Institut für Zellphysiologie, Ruhr-Universität, D-4630 Bochum, FRG;Laboratorium voor Fysiologie, Campus Gasthuisberg, KUL, B-3000 Leuven, Belgium

关键词: Cardiac myocyte;    Ca2+-release;    Sarcoplasmic reticulum;    Indo-1;    Na+/Ca2+-exchange;    Guinea-pig heart);   

DOI  :  10.1016/0014-5793(90)81467-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Simultaneous measurements of intracellular Ca²⁺-concentration ([Ca²⁺]₁) using Indo-1 and the current generated by electrogenic Na¹/Ca²⁺-exchange (I_Na??? have been performed on atrial myocytes from hearts of adult guinea-pigs. Whereas the flourescence-measurements provide information on global[Ca²⁺]_i, I_Na??? which is a linear function of Ca²⁺-concentration, indicates subsarcolemmal [Ca²⁺]. Under conditions in which intracellular Ca²⁺-transients due to Ca²⁺-release from the sarcoplasmic reticulum (SR) have been artificially slowed, a deviation between the two different Ca²⁺-signals can be found. During onset of release signals Ca²⁺-concentration seen by the membrane is higher than global [Ca²⁺]₁. Our results provide evidence that in atrial myocytes, lacking a T-system, Ca²⁺-release occurs first from a subsarcolemmal compartment of the SR. The resulting Ca²⁺-transient serves to trigger Ca²⁺-release from deeper SR-compartments.

【 授权许可】

Unknown