Relationship between cytosolic calcium and oxygen consumption in isolated rat hearts.
Maximum oxygen consumption was attained in isolated perfused rat hearts using high perfusate calcium and/or isoproterenol, or phenylephrine. The amplitude of calcium transients was directly related to oxygen consumption until oxygen consumed per beat reached maximum. At saturating oxygen consumption the amplitude of [Ca2+]i transients continued to increase, indicative of a calcium overload. In all cases +dP/dt correlated proportionately with +dCa2+/dt. Augmented developed pressure, related to isoproterenol-induced increase in cytosolic cAMP, cannot be attributed totally to elevated levels of [Ca2+]i transients. Adenosine (10(-5) M) added to the medium containing isoproterenol (10(-6) M) negated the isoproterenol-induced increase in cAMP and returned cardiac performance, oxygen consumption, and amplitude of [Ca2+]i transients to control state.
Wu
S T
ST
Department of Medicine, University of California, San Francisco.
Kojima
S
S
Parmley
W W
WW
Wikman-Coffelt
J
J
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D005470:Fluorometry; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D002118:Calcium