Anaerobic rat heart: mitochondrial role in calcium uptake and contractility.
In order to evaluate the manner by which fumarate enhances contractility in the anaerobic heart, we examined Ca++ movements in isolated heart mitochondria and in the isolated perfused heart. Our experiments showed that in isolated antimycin A plus cyanide treated mitochondria: (a) Ca++ uptake was promoted by electron transport generated by fumarate-dependent oxidation of NADH, (b) Ca++ stimulated fumarate-dependent oxidation of NADH, (c) the ratio of Ca++ uptake:NADH oxidized was 1.7 and (d) the Ca++ sequestered is transiently highly mobile and is rapidly released upon collapse of the membrane potential. In anaerobic hearts perfused with glucose plus fumarate, malate and glutamate Ca++ levels were the same as those in oxygenated hearts while in anaerobic organs perfused with or without glucose Ca++ content was appreciably lower. Succinate production in anaerobic heart perfusions was related to: (a) an increased retention of Ca++ by the heart, (b) a diminution in peak aortic pressure generated by cardiac contractions and (c) an increase in heart rate. The information obtained indicates that mitochondria have a capability for Ca++ movement which be used physiologically, particularly in fumarate perfused anaerobic hearts, to assist the mechanism for contraction and relaxation of the heart.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000693:Anaerobiosis; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003486:Cyanides / Q000494:pharmacology; D005650:Fumarates / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006339:Heart Rate; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D009200:Myocardial Contraction; D009243:NAD / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology; D051381:Rats; D013386:Succinates / Q000378:metabolism
D003486:Cyanides; D005650:Fumarates; D007773:Lactates; D010710:Phosphates; D013386:Succinates; D009243:NAD; D000244:Adenosine Diphosphate; D000968:Antimycin A; D005947:Glucose; D002118:Calcium