Ischemia/reperfusion-induced changes in intracellular free Ca2+ levels in rat skeletal muscle fibers--an in vivo study.
Accumulation of intracellular free calcium (Ca2+i) may play an essential role in the ischemia/reperfusion injury of skeletal muscle. Although it has been shown that Ca2+i levels significantly increase during ischemia/reperfusion, it is still a matter of debate whether Ca2+i increases during ischemia alone. It was the aim of this study to monitor the in vivo Ca2+i levels in the rat spinotrapezius muscle during ischemia of varying duration and reperfusion, using a ratiometric fluorescence technique, and to investigate the relationship between the postischemic flow patterns and Ca2+i, if any. The muscle was loaded with Indo-1/AM and imaged by a cooled digital camera. Pre- and postischemic tissue perfusion was assessed by means of an analogue camera. Our results show that short-term ischemia (5, 15 and 30 min) and subsequent reperfusion (60 min) does not alter Ca2+i homeostasis and that tissue perfusion promptly recovers after the insult. One or two hours of ischemia resulted in changes in Ca2+i levels, varying from preparation to preparation; increases in some and no changes in others. In these preparations three distinct flow patterns - normal, compromised and no-reflow - could be distinguished during the 60-min reperfusion. Our main conclusion is that in skeletal muscle Ca2+i levels may increase, the increase probably depending on the muscle fiber type exposed.
Ivanics
T
T
Second Department of Physiology, Semmelweis University of Medicine, Budapest, Hungary. ivanics@elet2.sote.hu
Miklós
Z
Z
Ruttner
Z
Z
Bátkai
S
S
Slaaf
D W
DW
Reneman
R S
RS
Tóth
A
A
Ligeti
L
L
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes; D007211:Indoles; D007425:Intracellular Membranes / Q000378:metabolism*; D007511:Ischemia / Q000378:metabolism*; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism*
D005456:Fluorescent Dyes; D007211:Indoles; C059587:Indo-1 pentaacetoxymethyl ester; D002118:Calcium