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Caffeine causes a considerable O(2) waste for positive inotropism in myocardium by complex pharmacological mechanisms. However, no quantitative study has yet characterized the mechanoenergetics of caffeine, particularly its O(2) cost of contractility in the E(max)-PVA-VO(2) framework. Here, E(max) is an index of ventricular contractility, PVA is a measure of total mechanical energy generated by ventricular contraction, and VO(2) is O(2) consumption of ventricular contraction. The E(max)-PVA-VO(2) framework proved to be powerful in cardiac mechanoenergetics. We therefore studied the effects of intracoronary caffeine at concentrations lower than 1 mmol/l on left ventricular (LV) E(max) and VO(2) for excitation-contraction (E-C) coupling in the excised cross-circulated canine heart. We enhanced LV E(max) by intracoronary infusion of caffeine after beta-blockade with propranolol and compared this effect with that of calcium. We obtained the relation between LV VO(2) and PVA with E(max) as a parameter. We then calculated the VO(2) for the E-C coupling by subtracting VO(2) under KCl arrest from the PVA-independent (or zero-PVA) VO(2) and the O(2) cost of E(max) as the slope of the E-C coupling VO(2)-E(max) relation. We found that this cost was 40% greater on average for caffeine than for calcium. This result, for the first time, characterized integratively cardiac mechanoenergetics of the O(2) wasting effect of the complex inotropic mechanisms of intracoronary caffeine at concentrations lower than 1 mmol/l in a beating whole heart.
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
July 1997,
Anesthesiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
September 1994,
Journal of molecular and cellular cardiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
October 1998,
The Japanese journal of physiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
November 1990,
The American journal of physiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
February 1982,
Circulation research,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
January 2012,
Acta medica Okayama,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
January 1988,
The American journal of physiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
June 2004,
The Japanese journal of physiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
June 1997,
Anesthesiology,
T Takasago, and
Y Goto, and
K Hata, and
A Saeki, and
T Nishioka, and
T W Taylor, and
G Iribe, and
S Mohri, and
J Shimizu, and
J Araki, and
H Suga
March 1988,
The Journal of pharmacology and experimental therapeutics,
