Cytosolic free Ca2+ in single rat heart cells during anoxia and reoxygenation.
Free Ca2+ in the cytosol ([Ca2+]i) of individual rat ventricle cells injected with aequorin was measured under anoxia. In glucose-free medium myocytes spontaneously shortened after about 60 min, although [Ca2+]i was still at or near resting levels. However, within minutes a net inward movement of Ca2+ across the sarcolemma developed and [Ca2+]i began to rise. Provided oxygen was readmitted before [Ca2+]i exceeded 2-3 microM, cells were able to restore [Ca2+]i to resting levels through caffeine-sensitive sequestration of Ca2+ in the sarcoplasmic reticulum. We suggest that Ca2+-independent shortening of anoxic cardiomyocytes reflects onset of rigor which triggers loss of [Ca2+]i homoeostasis.
Allshire
A
A
Department of Zoology, University of Liverpool, U.K.
Piper
H M
HM
Cuthbertson
K S
KS
Cobbold
P H
PH
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains
D002110:Caffeine; D005947:Glucose; D002118:Calcium